# Blog

Ans: Biot - Savart law states that the magnetic field $\mathrm{dB}$ due to a current element dI at any point would be as following: $$\begin{array}{l} \mathrm{dB} \propto \mathrm{dl} \\ \mathrm{dB}... read more ### A straight wire carries a current of . An electron moving at is at distance from the wire. Find the force acting on the electron if its velocity is directed towards the wire. Ans: We are given the current through the straight wire to be, I=10 \mathrm{~A} Speed of the electron, \mathrm{v}=10^{7} \mathrm{~m} / \mathrm{s} Distance of electron from the wire,... read more ### Give one difference each between diamagnetic and ferromagnetic substances. Give one example of each. Ans: Diamagnetic substances are the ones that are weakly repelled by a magnet. For example, gold. Ferromagnetic materials are the ones that are strongly attracted by a magnet. For example, iron. read more ### A steady current flows in the network What will be the magnetic field at the center of the network? Ans: The magnetic field at the center of the network is zero. This is because, magnetic field at the center of the loop would just equal and opposite i . e ., magnetic field due PQR is equal and... read more ### A cyclotron is not suitable to accelerate electron. Why? Ans: A cyclotron is not suitable to accelerate electron as its mass is known to be less due to which they gain speed and step out of the dee immediately, read more ### Two wires of equal lengths are bent in the form of two loops. One of the loops is square shaped whereas the other loop is circular. These are suspended in a uniform magnetic field and the same current is passed through them. Which loop will experience greater torque? Give reasons. Ans: We know the expression for torque as,$$ \begin{array}{l} \tau=\mathrm{NIAB} \\ \Rightarrow \tau \propto \mathrm{A} \end{array} $$Since, we know that the area of circular loops is more than... read more ### What will be the path of a charged particle moving along the direction of a uniform magnetic field? Ans: The path of a charged particle moving along the direction of a uniform magnetic field would be a straight line path as no force would act on the particle. read more ### State two properties of the material of the wire used for suspension of the coil in a moving coil galvanometer. Ans: Two properties of the material of the wire used for suspension of the coil in a moving coil galvanometer are: i. Non-Brittle conductor ii. Restoring Torque per unit twist should be small. read more ### V.I graph for a metallic wire at two different temperatures Which of these two temperatures is higher and why? Ans: From the graph: Slope =\frac{\mathrm{i}}{\mathrm{V}} It is known that, \frac{i}{V}=\frac{1}{R} It means that the smaller the slope, the larger the resistance. read more ### Two heated wires of the same dimensions are first connected in series and then it’s parallel to a source of supply. What will be the ratio of heat produced in the two cases? Ans: It is known that,$$ \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...

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...
Ans: Point $A \& B$ are at the same distance from the point $O$. Hence,