.Ans: Given is the work function $0.1 \mathrm{eV}$, $$ \phi_{o}=h v_{0} $$ Class 12 Physics $\underline{\text { wuw. vedantu.com }}$ 1 $10 a-x=10 a-2.5 a=7.5 a$ from charge $9 q$
)Ans: We are given the refractive index of glass to be, $\mu=1.5$ BreWster angle $=\theta$ Brewster angle is known to be related to refractive index as: $$ \begin{array}{l} \tan \theta=\mu \\...
west of the geographic north. The north tip of the magnetic needle of a dip circle placed in the plane of magnetic meridian points above the horizontal. The horizontal component of the earth’s field is measured to be 
Specify the direction and magnitude of the earth’s field at the location.At a certain location in Africa, a compass points west of the geographic north. The north tip of the magnetic needle of a dip circle placed in the plane of magnetic meridian points above the horizontal. The horizontal component of the earth’s field is measured to be Specify the direction and magnitude of the earth’s field at the location.Ans: In the above question it is given that: Angle of declination, $\theta=12^{\circ}$ Angle of dip, $\delta=60^{\circ}$ Horizontal component of earth's magnetic field, $B_{H}=0.16 \mathrm{G}$...
and 
carrying currents of 
and 
in the same direction are separated by a distance of 
. Estimate the force on a 
section of wire A.Ans: We are given the following: Current flowing in wire $A_{1} I_{A}=8.0 \mathrm{~A}$ Current flowing in wire $B, I_{B}=5.0 \mathrm{~A}$ Distance between the two wires, $r=4.0 \mathrm{~cm}=0.04...
wire carrying a current of 
is placed inside a solenoid perpendicular to its axis. The magnetic field inside the solenoid is given to be 
. What is the magnetic force on the wire?Ans: We are given the following: Length of the wire, $I=3 \mathrm{~cm}=0.03 \mathrm{~m}$ Current flowing in the wire, $1=10 \mathrm{~A}$. Magnetic field, $B=0.27 \mathrm{~T}$ Angle between the...
and making an angle of 
with the direction of a uniform magnetic field of 
Ans: We are given the following: Current in the wire, $I=8 \mathrm{~A}$ Magnitude of the uniform magnetic field, $B=0.15 \mathrm{~T}$ Angle between the wire and magnetic field, $\theta=30^{\circ}$...
. What is the magnitude of the field 
at a point 
from the wire?Ans: We are given the following: Current in the wire, $\mathrm{I}=35 \mathrm{~A}$ Distance of a point from the wire, $r=20 \mathrm{~cm}=0.2 \mathrm{~m}$ Magnitude of the magnetic field at this point...
-turns carrying current 
.Ans: Biot - Savart law states that the magnetic field $\mathrm{dB}$ due to a current element dI at any point would be as following: $$ \begin{array}{l} \mathrm{dB} \propto \mathrm{dl} \\ \mathrm{dB}...
. An electron moving at 
is at distance 
from the wire. Find the force acting on the electron if its velocity is directed towards the wire.Ans: We are given the current through the straight wire to be, $I=10 \mathrm{~A}$ Speed of the electron, $\mathrm{v}=10^{7} \mathrm{~m} / \mathrm{s}$ Distance of electron from the wire,...
Ans: Diamagnetic substances are the ones that are weakly repelled by a magnet. For example, gold. Ferromagnetic materials are the ones that are strongly attracted by a magnet. For example, iron.
Ans: The magnetic field at the center of the network is zero. This is because, magnetic field at the center of the loop would just equal and opposite $i . e .$, magnetic field due PQR is equal and...
Ans: A cyclotron is not suitable to accelerate electron as its mass is known to be less due to which they gain speed and step out of the dee immediately,
Ans: We know the expression for torque as, $$ \begin{array}{l} \tau=\mathrm{NIAB} \\ \Rightarrow \tau \propto \mathrm{A} \end{array} $$ Since, we know that the area of circular loops is more than...
Ans: The path of a charged particle moving along the direction of a uniform magnetic field would be a straight line path as no force would act on the particle.
Ans: Two properties of the material of the wire used for suspension of the coil in a moving coil galvanometer are: i. Non-Brittle conductor ii. Restoring Torque per unit twist should be small.
Ans: From the graph: Slope $=\frac{\mathrm{i}}{\mathrm{V}}$ It is known that, $\frac{i}{V}=\frac{1}{R}$ It means that the smaller the slope, the larger the resistance.
Ans: It is known that, $$ \begin{array}{l} H=I^{2} R t \quad\left(I=\frac{V}{R}\right) \\ \Rightarrow H=\frac{V^{2}}{R^{2}} \times R \times t \\ \Rightarrow H=\frac{V^{2}}{R} t \\ \Rightarrow H...
and 
respectively which of these is the best conductor?Ans: The resistance is directly proportional to specific resistance (resistivity), when length and area of cross-section is made constant. $R=\frac{\rho I}{A}$ Hence, silver is the best conductor as...
point change from corner to corner of a square 
when a 
charge exists at the centre of the square?Ans: Point $A \& B$ are at the same distance from the point $O$. Hence,
Ans: The electric field that is present inside a dielectric decreases when it is placed in an external electric field because of polarisation as it creates an internal electric field which is...
.Ans: Gauss's Theorem has a statement that electric flux through a closed surface enclosing a charge $q$ in vacuum is $\frac{1}{\epsilon_{0}}$ times the magnitude of the charge enclosed $\mathrm{is}...
Ans: Let us suppose a capacitor is connected to a battery and it supplies a small amount of change dq at constant potential $V$, then a small amount of work done by the battery is given by $$...
and 
are filled in between the two plates, each of area A of the parallel plate capacitor as shown in the figure. Find the net capacitance of the capacitor? Area of each plate 
Ans: In the question, the two capacitors are in parallel Net Capacitance, $C=C_{1}+C_{2}$ $$ \begin{array}{l} \mathrm{C}_{1}=\frac{\mathrm{K}_{1}...
Ans: Equidistant planes which are parallel to the $x-y$ plane are the equipotential surfaces. b) a field that uniformly increases in magnitude but remains in a constant (say, z) direction, Ans:...
electrode. The dielectric strength of the gas surrounding the electrode is 
. What is the minimum radius of the spherical shell required? (You will learn from this exercise why one cannot build an electrostatic generator using a very small shell which requires a small charge to acquire a high potential.)Ans: Given that, Potential difference is given as, $V=15 \times 10^{6} \mathrm{~V}$ Dielectric strength of the surrounding gas $=5 \times 10^{\top} \mathrm{Vm}^{-1}$ Electric field intensity is...
and 
are placed at points and 
apart. a) Identify an equipotential surface of the system.Ans: The situation is represented in the adjoining figure. An equipotential surface is the plane on which the total potential is zero everywhere. This plane is normal to line AB. The plane is...
is placed between the plates. What will be the effect on the capacitance?Ans: For air $C_{0}=\frac{A \in_{0}}{d}$ Thickness $t=\frac{d}{2}$ only when $k=\infty$ $$ \begin{array}{l} C_{0}=\frac{A \in_{0}}{d} \\ C_{\text {mat }}=\frac{A \in_{0}}{(d-t)} \end{array} $$ $$...
at right angles to a uniform electric field 
is deflected in a circular path of radius 
Prove that 
Ans: The path of the electron that is travelling with velocity $\mathrm{vm} / \mathrm{s}$ at right angle of $\bar{E}$ is of circular shape. It requires a centripetal in nature, $F=\frac{m v^{2}}{r}$...
and 
respectively. What is the electric charge inside the surface?Ans: Net flux can be given as $=\phi_{2}-\phi_{1}$ Since $\phi=\frac{q}{\epsilon_{0}}$ $$ \Rightarrow \mathrm{Q}=\left(\phi_{2}-\phi_{1}\right) \in_{0} $$ The electric charge inside the surface can...
Ans: The diagrams are given as: Equipoterhibil Surfaces 3 $\mathrm{~ ( 2 c ) r o m}$
. What will be the capacitance if the distance between the plates is reduced by half and the space between them is filled with a substance of dielectric constant 6 ?Ans: For air, capacitance can be expressed as, $C_{0}=\frac{A \in_{0}}{d}$ $$ C_{0}=8 \times p F=8 \times 10^{-12} F $$ Now $d^{\prime}=\frac{d}{2}$ and $K=6$ $$ \begin{array}{l} \Rightarrow...
Ans: Electric potential at point on the equatorial line of an electric dipole can be expressed mathematically as: $$ \begin{array}{l} V=V_{P A}+V_{P B} \\ \Rightarrow...
Ans: The introduction of dielectric in a capacitor will reduce the effective charge on plate and therefore will increase the capacitance.
Ans: The relation between capacitance, area, distance and dielectric constant is $$ C=\frac{A E_{0}}{d} \Rightarrow C \propto \frac{1}{d} $$ Hence, if distance increases, capacitance decreases....
Ans: The formula $E x \frac{1}{r^{3}}$ gives the relation between electric field and distance. $$ \therefore E \propto \frac{1}{\left(\frac{r}{2}\right)^{3}} \Rightarrow E \propto \frac{8}{r^{3}} $$...
. What distance apart should these be kept in the same medium, so that force between them becomes 
?Ans: If two point charges are $q_{1}$ and $q_{2}$ separated by distance $d$, it can be expressed as: $\mathrm{F}=\frac{\mathrm{Kq}_{1} \mathrm{q}_{2}}{\mathrm{~d}^{2}}$ Suppose if force becomes...
point change from corner to corner of a square when a charge exists at the centre of the square?Ans: Point $A \& B$ are at the same distance from the point $O$. Hence,
Ans: The electric field that is present inside a dielectric decreases when it is placed in an external electric field because of polarisation as it creates an internal electric field which is...
a) on the surface Ans: Electric field intensity on the surface of the balloon would be, $$ E=\frac{\sigma}{\varepsilon_{0}} $$ Electric potential on the surface of the balloon would be, $$ V=\frac{K...
of radius 
encloses a charge 
If there is another concentric sphere 
of radius 
and there is no additional change between and 
, then find the ratio of electric flux through 
and . 
Ans: We may recall that the expression for electric flux through a surface enclosing charge q by Gauss's law is given by, $$ \phi=\frac{q}{E_{0}} $$ Where, $\varepsilon_{0}$ is the permittivity of...
of radius encloses a charge If there is another concentric sphere of radius and there is no additional change between and , then find the ratio of electric flux through and . Ans: We may recall that the expression for electric flux through a surface enclosing charge q by Gauss's law is given by, $$ \phi=\frac{q}{E_{0}} $$ Where, $\varepsilon_{0}$ is the permittivity of...
and 
are separated by a distance of 
. Find the point on the line joining the two charges where electric field is zero.Ans: Let $p$ be the point (at $x$ distance from charge $+q$ ) on the line joining the given two charges where the electric field is zero. We know that the electric field at a point at r distance...
and charge a is released from rest in a uniform electric field of intensity E. Calculate the kinetic energy attained by this particle after moving a distance between the plates.Ans: We have the electrostatic force on a charge a in electric field E given by. $\mathrm{F}=\mathrm{q} \mathrm{E} \quad \ldots \ldots(1)$ Also, we have Newton's second law of motion given by, $$...
Ans: No. The net flux entering out through a body depends on the net charge contained in the body. If the net flux is given to be zero, then it can be inferred that the net charge inside the body is...
a) What is the net charge inside the box?Ans: It is given that: Net outward flux through surface of the box, $\phi=8.0 \times 10^{3} \mathrm{Nr}^{2} / \mathrm{C}$. For a body containing net charge a, flux is given by...
through a cube of side oriented so that its faces are parallel to the coordinate planes?Ans: It is given that all the faces of the cube are parallel to the coordinate planes. Clearly, the number of field lines entering the cube is equal to the number of field lines entering out of the...
Ans: Since unlike charges attract and like charges repel each other, the particles 1 and 2 moving towards the positively charged plate are negatively charged whereas the particle 3 that moves...
Ans: When dealing with macroscopic or large-scale charges, the charges used are huge in number as compared to the magnitude of electric charge. Hence, the quantization of electric charge is of no...
with respect to a uniform electric field of 
experiences a torque of 
. Calculate dipole moment of the dipole?Ans: It is given that $$ \begin{array}{l} \theta=30^{\circ} \\ \tau=9 \times 10^{-26} \mathrm{Nm} \\ E=10^{4} \mathrm{~N} / \mathrm{C} \end{array} $$ Dipole moment P needs to be calculated. It is...
across the plates of two capacitors 
and versus increase of charge 
stored on them. Which of the two capacitors have higher capacitance? Give reason for your answer.Ans: It is known that $c=\frac{Q}{V}$ Clearly, for a given charge $\mathrm{Q}$. $c \propto \frac{1}{V}$ Now, from the given graph, it is seen that $\mathrm{V}_{\mathrm{A}}
Ans: Two electric lines of force can never intersect each other. Suppose if they intersect, then at the point of intersection, there can be two tangents drawn. These two tangents are supposed to...
Ans: Force on both the electron as well as the proton in the uniform field would be equal because $\mathrm{F}=\mathrm{kq}$ and it is known that charge on both electron and proton are the same. On...
Ans: Charge on a body is said to be 1 coulomb if it experiences a force of repulsion or attraction of $9 \times 10^{9} \mathrm{~N}$ from another equal charge when they are separated by a distance of...
? 
?Ans: 1.The S.I. unit of electric dipole moment is $\mathrm{Cm}$. 2. The S.I. unit of electric field intensity is N/C.
and 
?Ans: Suppose that the rod $\mathrm{P}$ is negatively charged. As it attracts rod $\mathrm{R}$, it can be said that $\mathrm{R}$ is positively charged. Also, since $P$ repels rod $Q$, it can be said...
Ans: Dielectric constant of a medium is given by $$ \begin{array}{l} k=\frac{F_{y}}{F_{M}}=\frac{\text { force between the charges in vaccum }}{\text { force between two charges in medium }} \\...
Correct option is (i)
Electric potential at a place in an electric field is the amount of effort done to bring the unit positive charge from infinity to that point, whereas electric potential energy is the energy...
B 
C 
D None of theseCorrect option is (A) $10^{\circ}$ $\frac{\mathrm{F}_{\mathrm{e}}}{\mathrm{F}_{\mathrm{p}}}=10^{0}=1$, because force depends only on charges, distance and nature of medium and not type of charge. As...
and carrying charge are separated by some distance. If they are in equilibrium under mutual gravitational and electrostatic forces, then 
(in 
) is of the order of: 
Correct option is (B) $10^{-10}$ Given : Gravitational force $=$ Electrostatics force Let the distance between the rwo charges be r. $$ \begin{array}{l} \Rightarrow \frac{\mathrm{G}(\mathrm{m})...
In electrostatic force, the force of medium depends on charges while the force of the medium due to gravity does not depend on masses. There is no concept of induced mass.
Correct option is (D) Dependence on the intervening medium In electrostatic force, the force of the medium depends on charges while the force of the medium due to gravity does not depend on masses....
is : Correct option is (C) 625 We need force of repulsion $=10^{-19} \mathrm{~N}$ Let $n$ no. of increase electrons be placed on each sphere $$ \begin{array}{l} \Rightarrow...
Correct option is(c) same Since the magnitude of the charge of electron and proton is the same, e, the electrostatic force between two protons is the same compared to the electrostatic force between...
Correct option is D current leads ahead of the emf $\mathrm{D}$ In circuits with primary capacitive loads, currently leads to the voltage. This is because the current must flow first to the two...
Correct option is A $\mathrm{W}=\frac{\varepsilon_{0} \mathrm{~A} \mathrm{~V} \mathrm{~h}^{2}}{2 \mathrm{~d}}(1-1 / \mathrm{k})$ C $Q=\frac{\varepsilon_{0} A V}{d}$ D $\quad E=\frac{V}{k d}$ As...
and 
, then 
is: 
Correct option is B $\frac{2}{3}$ Let the charge stored by a capacitor with dielectric constant 3 be $Q$. Thus energy stored be $\frac{\mathrm{Q}^{2}}{2 \mathrm{C}_{1}}$ Since the charge remains the...
The correct option is (A) charge Q When the capacitor is kept at a voltage, it gains charge. Now when the system is isolated, the charge present on the capacitor cannot change because of the law of...
$\mathrm{~ O ~ W e i s c o d i s ~ T o p}$ Correct option is B increases As the dielectric slab is introduced there is some charge distribution in the slab and because of this, the electric field...
The correct option is B decreases finitely Quality factor $Q$ is given by: $$ \mathrm{Q}=\frac{\omega_{0} \mathrm{~L}}{\mathrm{R}} $$ Thus, as $\mathrm{R}$ increases Q definitely decreases.
Transformer works on. 
and DC The correct option is A AC only Transformer works on the principle of Electromagnetic induction i.e an emf is induced in the coil if the magnetic flux linked with the coil changes. Magnetic flux in...
Correct option is B $\frac{\mathrm{Q}^{2}}{2 \mathrm{\varepsilon}_{0} \mathrm{~A}}$ The magnitude of electric field by any one plate is $\mathrm{E}=\frac{\sigma}{2...
Correct option is D $\frac{\mathrm{f}_{0}}{\mathrm{f}_{2}-\mathrm{f}_{1}}$ Quality factor is a relation between stored energy and energy dissipation in a device or system. As per definition of...
Q-factor: In LCR Circuit, the ratio of resonance frequency to the difference of its neighboring frequencies so that their corresponding current is $1 / \sqrt{2}$ times of the peak value, is called...
Biot savart law is the base of all magnetism and the effects of current. It states that the magnetic field intensity due to an element of a current-carrying wire at a point near the element is...
The correct option is A Mutual induction Mutual inductance is where the magnetic field generated by a coil of wire induces a voltage in an adjacent coil of wire. A transformer is a device...
. supplyThe correct option is D) A device for stepping up or down the voltage of $A C$. supply A transformer is a device that is used to either raise or lower voltages and currents in an electrical circuit....
For the construction of the transformer, you must have two coils having mutual inductance and a laminated steel core. The two coils are insulated from each other and from the steel core. The device...
Principle: The transformer is based on the principle of electromagnetic induction. The phenomenon of producing an induced emf due to the changes in the magnetic flux associated with a closed circuit...
radian 
radian 
radian The correct option is D zero We know that phase difference is given by: $$ \phi=\arctan \left(\frac{\left(\mathrm{X}_{\mathrm{L}}-\mathrm{X}_{\mathrm{C}}\right)}{\mathrm{R}}\right) $$ at resonance...
Correct option is c $\frac{1}{2 \pi} \sqrt{\frac{1}{L C}-\frac{R^{2}}{L^{2}}}$ Megritude of admittanos $Y=\frac{1}{Z}$ is given by: $$ |\mathrm{Y}|=\frac{\mid \mathrm{H}^{2}...
Correct option is a $\frac{1}{2 \pi \sqrt{L C}}$ For rescnance $$ \mathrm{X}_{\mathrm{L}}=\mathrm{X}_{\mathrm{E}} $$ $$ \begin{aligned} \mathrm{kL} &=\frac{1}{\mathrm{wC}} \\ \mathrm{w}...
The correct option is A Terrestrial Magnetism
The correct option is C inductance is very high and resistance is negligible. The power consumption in an AC circuit is zero when the circuit contains only inductance or capacitance since the...
The terminal potential difference of a cell is equal to the emf of the cell when: → The cell is an open circuit. → The internal resistance of the cell is zero. → The load resistance much greater...
The angle of dip is the angle between the direction of the earth's magnetic field and the plane of the horizon
The correct option is False In a chemical reaction, the total mass of the reactants is equal to the total mass of the product hence the mass remains conserved in a chemical reaction.
at its centre. This coil is made itself to 10 turns and the same current is set up in it. The magnetic field at its centre would be 
Correct option is B $\mathrm{B}=10 \mathrm{~B}_{0}$ Electric current in a circular loop creates a magnetic field which is more concentrated in the center of the loop than outside the loop....
of its value at the centre? 
Correct option is B $\sqrt{3} \mathrm{a}$ Magnetic field due to the circular current (I) carrying coil of radius $\mathrm{a}$, at a distance $r$ from the center of the coil is given by: $$...
(a)The phase difference between current and voltage $\phi$ is given by $$ \begin{array}{l} \tan \phi=\frac{\mathrm{X}_{\mathrm{C}}-\mathrm{X}_{\mathrm{L}}}{\mathrm{R}} \\...
and range 
is to be used to read potential difference upto 1 volt. It will have to be connected to A 
resistance in series B resistance in parallel C 
resistance in parallel D resistance in seriesCorrect option is A $99.8 \Omega$ resistance in series $$ \begin{array}{l} \mathrm{V}=\mathrm{I}_{g}\left(\mathrm{R}+\mathrm{R}_{g}\right) \\ \therefore 1=10 \times 10^{-3} \times(\mathrm{R}+0.2) \\...
$$ \begin{array}{l} B_{A}=\frac{\mu_{1} I}{2} \times \frac{r^{2}}{\left(x^{2}+r^{2}\right) \frac{3}{2}}\\ \mathrm{B}_{0}=\frac{\mu_{1} \mathrm{I}}{2} \times \frac{\mathrm{r}^{2}}{\mathrm{r}^{3}}\\...
The average velocity of all the free electrons in the conductor is called the drift velocity of free electrons of the conductor. When a conductor is connected to a source of emf an electric field is...
Radiation of wavelength of 21 cm : It corresponding to radio waves of short wavelength.
Correct option is D one-ninth the resistance of ammeter Full scale deflection voltage be V Now initiall range is I $$ \mathrm{V}=\mathrm{IR} $$ Now, Range is made $10 \mathrm{I}$ $$ \begin{array}{l}...
Microwaves are used in operating a RADAR.
correspond to?$\mathrm{X}$-rays part of electromagnetic spectrum does the wavelength $10^{-10} \mathrm{~m}$ correspond to.
-rays, visible light, radio waves -rays 
gamma rays, visible light, radio waves -rays, gamma rays -raysCorrect option is C Radio waves, visible light, $\mathrm{X}$-rays, gamma rays The electromagnetic spectrum is a continuum of all electromagnetic waves arranged according to frequency and wavelength....
Consider a circular coil of radius a and carrying current I in the direction shown in Figure. Suppose the loop lies in the plane of paper. It is desired to find the magnetic field at the centre...
![\[B=(200 \mu T) \sin \left[\left(4.0 \times 10^{1} 5_{s}{ }^{-1}\right)(t-x / c)\right]\]](https://www.learnatnoon.com/s/wp-content/ql-cache/quicklatex.com-0247b2cf5ede1bd8c8ab6111ddde9489_l3.png "Rendered by QuickLaTeX.com")
Given: The magnetic field in a plane electromagnetic wave is given by $$ \mathrm{B}=(200 \mu \mathrm{T}) \sin \left[\left(4.0 \times 10^{1} 5_{\mathrm{s}}^{-1}\right)(\mathrm{t}-\mathrm{x} /...
and 
are located 
apart. At what point 
on the line joining the two charges is the electric potential zero? Take the potential at infinity to be zero.Let $\mathrm{p}$ be the point of zero potential be $\mathrm{p}$ at distance $\mathrm{r}$ from the charge $1 .$ $\mathrm{d}=16 \mathrm{~cm}$ Electric potential, $\mathrm{v}=\mathrm{q}_{1} / 4 \pi...
and 
. Correct option is D zero and min. When the dipole is in the direction of field then net force is $\mathrm{q} \mathrm{E}+(-\mathrm{q} \mathrm{E})=0$ and its potential energy is minimum $=-$ p.E...
Correct option is A $0^{\circ}$ Electric field $\overrightarrow{\mathrm{E}}$ is along the dipole axis $\therefore \theta=0^{\circ}$
If magnetic field lines cross, there will be two directions of the same field at the crossing point, which is not conceivable. As a result, the field lines do not cross or intersect
When the positive terminal of a cell or battery is connected to the p-side of the junction and the negative terminal to the n side, the diode is said to be forward biassed. The depletion region...
The Bohr Atomic Model's Postulates Electrons orbit the nucleus in a predetermined circular path known as "orbits," "shells," or "energy levels." Each circular orbit has a given quantity of energy,...
1) The Bohr atomic model hypothesis made correct predictions for lower sized atoms like hydrogen, but poor spectrum predictions were achieved when larger atoms were taken into account. 2) When the...
Current passes through the circuit while a capacitor is charging (or draining). However, no actual charge transfer occurs in the insulated region between the capacitors, which is incompatible with...
The oscillating electric and magnetic fields at right angles to one other make up electromagnetic waves. Properties Electric fields and magnetic fields oscillate at right angles to one other to...
Current passes through the circuit while a capacitor is charging (or draining). However, no actual charge transfer occurs in the insulated region between the capacitors, which is incompatible with...
Correct option is B Light Electromagnetic waves travel in free space or vacuum with the velocity of light, $\mathrm{c}=3 \times 10^{8} \mathrm{~m} / \mathrm{s}$
? 
, 
Correct option is A $0.3$ $$ \mathrm{C}=\mathrm{v} \lambda $$ $$ \lambda=\frac{\mathrm{c}}{\mathrm{v}}=\frac{3 \times 10^{8}}{10^{12}} $$ $$ \begin{array}{l} =3 \times 10^{-4} \mathrm{~m} \\ =0.3...
and 
respectively, then according to Faraday’s law of electro magnetic induction: 
E must be zero if 
and changing 
if 
if is changing. 
then must be zeroCorrect option is c $E \neq 0$ if $\phi$ is changing. Farady's law states that time varying magnetic flux can induce an e.m.f. $\mathrm{E}=$ Electric field, Induced $$ \mathrm{E}=-\frac{\mathrm{d}...
Moving charges produce electromagnetic waves, which are a mix of electric and magnetic field waves. A charged particle is the starting point for all electromagnetic waves. An electric field is...
There are two Faraday's laws of Electromagnetic induction, 1) First Law: Whenever magnetic flux linked with the circuit changes, an emf is induced in it. 2)Second Law: The magnitude of emf is...
and respectively, then according to Faraday’s law of electro magnetic induction: and changing if if is changing. then must be zeroCorrect option is c $E \neq 0$ if $\phi$ is changing. Farady's law states that time varying magnetic flux can induce an e.m.f. $\mathrm{E}=$ Electric field, Induced $$ \mathrm{E}=-\frac{\mathrm{d}...
Correct option is B The resistance of the coil The induced emf produced when a magnet is inserted into a coil does not depend upon the resistance of the coil.
to 
in 
in an inductor the induced emf is found to be 
, then find the value of self-inductance is : 
Correct option is C $2.5 \mathrm{H}$ $$ \begin{array}{l} \Delta \mathrm{I}=(4-0)=4 \mathrm{~A} \\ \mathrm{t}=0.1 \mathrm{~s} \\ \mathrm{e}=100 \mathrm{~V} \\...
Correct option is A True Soft iron core is used in electromagnets because soft iron does not retain magnetism permanently, that is, it loses the magnetism as soon as magnetic field is removed. Hence...
Correct option is (C) Volt-sec/ampere $$ \begin{aligned} e &=L \frac{d i}{d t} \\ \Rightarrow & L=\frac{V \text { olt }-\text { sec }}{\text { Ampere }} \end{aligned} $$
Correct option is D (i), (ii) and (iv) are correct Soft iron conducts electricity It is a magnetic material It is not used for magnetic permanent magnets It is used as electro magnet
The correct option is A High coercivity and high retentivity Since of its high coercivity and low retentivity, Alnico is used to make permanent magnets because it can be quickly magnetised in an...
CORRECT OPTION IS iii) high retentivity and low coercivity The capacity of a substance to remain magnetised after the external magnetising field has vanished is known as retentivity. A material with...
Correct option is D nature of the material Hint: Resistivity is an intrinsic property of a metal. Step 1: Explanation of Resistivity Resistivity of a metallic wire does not depend on its geometry...
Correct option is (C) material The resistivity or specific resistance of a material is an intensive property (property which does not depend on the system size or the amount of material in the...
Resistance can be defined as $$ \begin{array}{l} \mathrm{R} \propto \frac{1}{\mathrm{~A}} \\ \Rightarrow \mathrm{R}=\rho \frac{1}{\mathrm{~A}} \end{array} $$ where $\rho=$ specific resistance or...
Correct option is (iv) None of the above The product of resistivity and conductivity of a cylindrical conductor is constant The product becomes $\rho \times \sigma$, where pis resistivity and...
. The electric field intensity near it is 
Correct option is A $\frac{\sigma}{\varepsilon_{0}}$ Charge density $=\sigma$ Electric field intensity near it is - Using gauss law, $\lambda=\frac{\sigma}{\varepsilon_{0}}$
Correct option is D None of these $$ \begin{array}{l} \mathrm{F}=\mathrm{q} \mathrm{E} \\ \mathrm{E}=\frac{\mathrm{F}}{\mathrm{q}}=\frac{\mathrm{N}}{\text { Coulomb }}=\mathrm{NC}^{-1}=\text { SI...
tesla 
teslaCorrect option is B zero Using ampers law, there is no current enclosed in the pipe $\int \overline{\mathrm{B}} \cdot \overline{\mathrm{dl}}=\mu_{0}$ Ienclosed
Correct option is B zero $\operatorname{Sin} \theta=0$ on any pt, on the axis of conductor carrying current $$ \mathrm{B}=\frac{\mu_{0}}{4 \Pi} \mathrm{i} \frac{\mathrm{d}] \operatorname{Sin}...
‘ carry a current of ‘ 
‘ in the same direction. They will 
Correct option is B attract each other with a force of $y_{0} i^{2} /(2 \pi \mathrm{d})$ $$ \frac{\mathrm{F}}{\mathrm{l}}=\frac{\mu_{0} \mathrm{i}_{1} \mathrm{i}_{2}}{2 \pi \mathrm{d}} $$ $$...
in opposite directions. The distance between the wires is . at a certain instant of time, a point charge 
is at a point equidistant from the two wires in the plane of the wires. Its instantaneous velocity 
is perpendicular to this plane. The magnitude of the force, due to the magnetic field acting on the charge at this instant is: 
Correct option is (D) zero Magnetic field at P is perpendicu;ar to paper inward due to both the wires. Charged particle is also projected in the same direction. So, force on the charged particle is...
is moving with a velocity v parallel to a magnetic field . Force on the charge due to magnetic field is 
Correct option is C zero $$ \begin{array}{l} \mathrm{F}_{\mathrm{n}}=\mathrm{q}(\overrightarrow{\mathrm{v}} \times \overrightarrow{\mathrm{B}}) \\ =\mathrm{qvB} \sin \theta \\ =0 \text { (because }...
acting on charge 
moving with velocity 
perpendicular to magnetic field is 
Correct option is (I) $F=q v B$ Magnetic force $\mathrm{F}=\mathrm{q}(\mathrm{v} \times \mathrm{B})=\mathrm{qvB} \sin \theta$ where $\theta$ is the angle between $v$ and $B$. Given:...
resistance is stretched two times its initial length. Its new resistance is 
Correct option is (iv) $200 \Omega$ Resistance of wire $\mathrm{R}=\rho \frac{\mathrm{L}}{\mathrm{A}}=\rho \frac{\mathrm{L}^{2}}{\mathrm{AL}}=\rho \frac{\mathrm{L}^{2}}{\mathrm{~V}}$...
iii) newton/coulomb The amount of force experienced by a unit charged particle when it is placed in the electric field is known as Electric field intensity. The S.I unit of electric field intensity...
as heat engine, is used as a. refrigerator. If the work done on the system is 
, the amount of energy absorbed from the reservoir at lower temperature is: 
Correct option is A $90 \mathrm{~J}$ efficiency of carnot cycle is given as $$ \eta=\frac{W}{Q_{H}} $$ where $W$ is work done and $Q_{H}$ is amount of heat added to system. $$ \begin{array}{l}...
, when kept under the same tension. What fractional increase in the tension of one wire would cause an occurrence of 5 beats , when both wires vibrate together? Solution (A) 2 $\mathrm{n} \propto \mathrm{V}$ and $\mathrm{V} \propto \sqrt{T}$ $$ \Rightarrow \mathrm{n} \propto \sqrt{\mathrm{T}} . .(1) $$ 5 beats/sec are obtained when the frequency of one...
and 
second respectively. Write the equation of stationary waveSince the waVe equation of a travelling wave:- $y=a \sin 2 \pi(t / T-x / \pi)$ $\mathrm{a}=$ Amplitude $t=$ time $\mathrm{T}=$ Time Period $x=$ Path difference $\pi=$ wavelength Let...
, where 
and 
are in 
and 
is in seconds . The phase difference between two particles 
apart at any instant is 
Correct option is D $72^{\circ}$ Given equation can be written as $y=6 \sin (4 \pi t-0.2 \pi x)$ $\therefore$ Phase $\phi=-0.2 \pi x$ $\Rightarrow \phi_{1}=-0.2 \pi \mathrm{x}_{1}$ and...
if the gas has 
degrees of freedom.$\mathrm{~ O ~ W e i r i s o s t y ~ T o p p r}$ The molar specific heats of a gas having $\mathrm{f}$ degrees of freedom is given by : $$ \mathrm{C}_{\mathrm{r}}=\frac{1}{2} \mathrm{f} \mathrm{R}...
of the molecules of a gas will become equal to the of an electron accelerated from rest through 
potential difference? 
Correct option is C $7.73 \times 10^{3} \mathrm{~K}$ $$ \frac{3}{2} \mathrm{KT}=1 \mathrm{eV}=1.6 \times 10^{-19} \mathrm{~J} $$ Or" $$ \mathrm{T}=\frac{2 \times 1.6 \times 10^{-19}}{3 \times 1.38...
$S=$ surface tension of soap Liquid $1=$ length of $\mathrm{PQ}$ Total Inward Force on the wire P Q $$ F=S \times 21 $$ To increase surface area we have to pull wire $\mathrm{P} \mathrm{Q}$ outwards...
,br>C 
Correct option is B $\frac{1(\text { stress })^{2}}{2}$ The elastic energy stored per unit volume in a stretched wire is $$ \mathrm{u}=\frac{1}{2} \times \text { stress } \times...
transverse wave is propagating on the string and is described by the equation 
where 
and 
are measured in meter and t in second. Ten sion in the string is 
Correct option is A $0.12 \mathrm{~N}$ Linear density $\mu=1.3 \times 10^{4} \mathrm{Kg} / \mathrm{m}$ Wave equation $y=0.021 \sin (x+30 t)$ Velocity of wave...
to 
What will be the change in the internal energy of gas? The molar heat of oxygen at constant pressure, 
and 
mol 
$\mathrm{R}=8.31 \mathrm{~J} \quad \mathrm{~mol}^{-1} \mathrm{deg}^{-1}=\frac{8.31}{4.18} \mathrm{cal} \mathrm{mol}^{-1} \mathrm{deg}^{-1}$ $=1.99 \mathrm{cal} \mathrm{mol}^{-1} \mathrm{deg}^{-1}$...
Law of conservation of angular momentum states that in the absence of an external torque, the total angular momentum is conserved or the total angular momentum of an isolated system remains constant...
When there is no net torque applied to a system, such as a rotating item or objects, the law of conservation of angular momentum asserts that angular momentum is conserved. An ice skater performing...
and temperature is 
. How much heat is radiated per minute by itStefan's constant = $5 \cdot 67 \times 10^{-8}$ joule $/\left(\mathrm{m}^{2}-\sec -\mathrm{K}^{4}\right)$ The power radiated is given by Stefan's law: $$ \mathrm{P}=\sigma \mathrm{AeT}^{4} $$...
The correct option is B zero The velocity of the particle is constant i.e $\mathrm{v}=$ constant Using $\mathrm{v}=\mathrm{rw} \quad \Longrightarrow \mathrm{w}=$ constant $\therefore$ Angular...
rate of change of tangential velocity is called as the centripetal acceleration. $$ \mathrm{F}=\frac{\mathrm{mv}^{2}}{\mathrm{r}} $$ centripetal acceleration is given by, $$...
Bernoulli's principle asserts that the entire mechanical energy of a moving fluid, which includes gravitational potential energy of elevation, fluid pressure energy, and fluid motion kinetic energy,...
In the year 1660, an English scientist named Robert Hooke discovered Hooke's law, commonly known as the law of elasticity. "When an object has a relatively minor deformation, the magnitude of the...
The perpendicular axis theorem asserts that the moment of inertia of a planar lamina (i.e. 2-D body) at an axis perpendicular to the plane of the lamina is equal to the sum of the moments of inertia...
. What is the radial acceleration directed towards the sun?$$ \begin{array}{c} \text { Speed of revolution }=30 \mathrm{Km} / \mathrm{s} \\ =3 \times 10^{4} \mathrm{~m} / \mathrm{s} \end{array} $$ Time of revolution $=$ One year $=356$ days (convert into...
superimposes with another wave and produces stationary wave. At 
node is formed. The equation of the second wave is 
Correct option is D $-\mathrm{a} \cos (\mathrm{kx}+\omega \mathrm{t})$ To form a stationary wave with $y=a \cos (k x-w t)$ the wave should be in the opposite direction of this wave and amplitude...
If the top of the capillary tube is closed, there will be a little rise in the capillary tube. Because the downward force exerted by compressed air above the liquid in the tube opposes the rise of...
radian radian.Correct option is ii) acute angle Liquid rises in a capillary tube if the angle of contact is acute, but liquid falls in a capillary tube if the angle of contact is obtuse
Chloride radical is detected by the chromyl chloride test. In this test, chromyl chloride gas (orange red color) is produced. Equation Involved – 4NaCl + K2Cr2O7 + 6H2SO4 → 4NaHSO4 + 2KHSO4 + 3H2O +...
The lanthanide contraction is the decrease in the atomic or ionic radii with increase in the atomic number of lanthanides
Lanthanide elements resembles a lot in properties with lanthanum. Lanthanide is group of 14 elements from atomic number 58 to 71. In these elements on increasing atomic number electron enters into...
2KMnO4 + 8H2SO4 + 10KI → 6K2SO4 + 8H2O + 5I2 2KMnO4 + 5SO2 + 2H2O → 2MnSO4 + 2H2SO4 + K2SO4 2KmO4 + 16HCl → 2KCl + 2MnCl2 + 8H2O + 5Cl2 5COOH – COOH + [5O] → 10CO2 + 5H2O
The ozone layer's depletion has negative consequences for the environment. Let's look at the key consequences of ozone depletion on humans and the environment. Human Health Effects Due to the ozone...
The Xylem transports water and minerals in plants. - Root hairs are hairs that grow on a plant's roots. Because they are in close touch with the water layer between the soil particles, these root...
Enzymes are proteins with specific functions. They're found in all living cells and are required for every chemical reaction that takes place in the body. Each enzyme is responsible for a specific...
One of the fundamental differences between arteries and veins is that arteries deliver oxygenated blood to all body areas, whereas veins, with the exception of pulmonary arteries and veins, carry...
When a metal reacts with water, a metal hydroxide is generated, as well as hydrogen gas. The chemical reactivity of a metal determines the degree of its interaction with water. Some metals respond...
The valency of magnesium is 2.
H2SO4(aq)+Zn(s)→ZnSO4(aq)+H2(g)
In our daily lives, we see a lot of chemical reactions. Burning, corrosion, food heating, and digestion are all instances of such interactions. Precipitation reactions are a common type of chemical...
, where 
is the amount of heat produced by steady curnent I through a resistor 
in time t.Electric power is the rate at which electrical energy is transferred by an electric circuit per unit of time. The watt, or one joule per second, is the SI unit of power. Electric generators are the...
In an electric motor, electrical energy is turned into mechanical energy. Electric motor operation: When a current is fed through the coil PQRS, the coil begins to rotate anticlockwise because a...
The intensity of the magnetic lines is constant throughout and proportional to their proximity. Reason - The two magnetic field lines do not connect because if they did, the compass needle would...
They are long-term. The renewable energy basis in the United States is practically intact, from the sun to wind to biofuels. And, because these alternative energy sources are regenerated organically...
At the time of sunset or sunrise, the Sun and its surroundings appear red because of the scattering of light. At the time of sunset or sunrise, the light rays from the Sun have to travel a long...
The quantity of current in a serial circuit reduces when each component receives a low voltage, causing the gadget to become heated and malfunction. As a result, in home circuits, the series layout...
According to refraction laws, At the point of incidence, the incident ray, refracted ray, and normal to the interface of two media all lie on the same plane. A constant is the ratio of the sine of...
1. We'll start with a potted plant like a croton, which has partially green and partially white leaves. Chlorophyll is present in the green portion of the leaf, but not in the white portion. 2....
Decomposers have a variety of roles in the ecosystem: they decompose biodegradable substances into usable chemicals; they release nutrients into the soil by dissolving dead and decaying waste,...
The benefits of sexual reproduction include the generation of genetic variety in the progeny. Because of their diversity, the species can adapt to different habitats, giving them a survival...
The elevation of boiling point on adding one mole solute to 1000 g solvent is called molal boiling point elevation constant. It is denoted by Kb. Its unit is K kg mol-1. The elevation of boiling...
Excretion is a vital life mechanism that is observed in all living organisms. Excretory products are produced as a result of both metabolic and non-metabolic processes. Animal wastes are divided...
(i) Vitamin C – Cures fever, asthma and diabetes. (ii) Curcumin – Used as an antiseptic and antibiotic. (iii) Cineole and Eugenol – Cures skin diseases, ear pain, cough and cold
The process through which nutrients are transformed into useable energy in a cell is known as cellular respiration. It's a biological process in which energy is released in stages as chemical...
Sushrut was a renowned surgeon of ancient India and author of the book Sushrut Samhita. He was the first physician to advocate what is today known as 'Caesarean operation'. He was also expert in...
The following is the photosynthesis equation: C6H12O6 + 6O2 = 6CO2 + 6H20 + (energy) Glucose and oxygen are made from carbon dioxide, water, and light energy.
Other key methods for forest conservation include: Legislation prohibiting the legislature from cutting down trees indiscriminately. Willingness of the government to prevent deforestation by...
CaSO4.1/2H2O + 3/2H2O = CaSO4.2H2O is the chemical equation for the reaction of Plaster of Paris and water. Heat is released when plaster of Paris reacts with water and crystallises. Plaster of...
Aspartame and Saccharin
In water, the oxygen is electronegative due to the intermolecular hydrogen bonding which is formed in the water molecules and exists in a liquid state. Whereas, the sulphur is less electronegative...
Prevention of Corrosion: (i) By coating metal surface with oil or grease: A thin layer of oil or grease is coated on the surface of the metal. (ii) By painting the metal surface: A layer of point is...
Electrochemical theory of corrosion: A number of galvanic cells are formed in impure iron. In rusting of iron pure iron acts as an anode while impure part of iron acts as a cathode. A thin layer...
Corrosion is defined as the process by which the layers of undesired compounds are formed on the surface of the metal when exposed to the atmospheric conditions
Faraday’s first law of electrolysis states that the amount of any substance deposited or liberated at any electrode is directly proportional to the quantity of electricity passed through the...
(i) Urotropine is formed when ammonia reacts with formaldehyde. 6HCHO + 4NH3 → (CH2) 6N4 + 6H2O (ii) Acetyl chloride is produced when acetic acid reacts with PCl5. CH3COOH + PCl5 → CH3COCl + POCl3 +...
(i) Acetaldehyde is obtained when acetyl chloride is reduced with hydrogen in presence of barium sulphate associated with palladium. CH3 – COCl + 2H → CH3CHO + HCl (ii) Sodium benzoate and Benzoyl...
Acetic acid preparation by Vinegar Quick process: An aqueous solution of ethyl alcohol is mixed with oxidized in the presence of the enzyme micro derma aceti. The wooden vat is fitted with two...
The reaction of diethyl ether with HI acid forms alkyl halide with excess of HI. Reaction Involved – C2H5 – O – C2H5 + 2HI → 2C2H5I + H2O