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Show mathematically that the potential at a point on the equatorial line of an electric dipole is Zero?
Ans: Electric potential at point on the equatorial line of an electric dipole can be expressed mathematically as: $$ \begin{array}{l} V=V_{P A}+V_{P B} \\ \Rightarrow...
What happens to the capacitance of a capacitor when a dielectric slab is placed between its plates?
Ans: The introduction of dielectric in a capacitor will reduce the effective charge on plate and therefore will increase the capacitance.
The plates of a charged capacitor are connected by a voltmeter. If the plates of the capacitor are moved further apart, what will be the effect on the reading of the voltmeter?
Ans: The relation between capacitance, area, distance and dielectric constant is $$ C=\frac{A E_{0}}{d} \Rightarrow C \propto \frac{1}{d} $$ Hence, if distance increases, capacitance decreases....
The distance of the field point on the equatorial plane of a small electric dipole is halved. By what factors will the electric field due to the dipole changes?
Ans: The formula $E x \frac{1}{r^{3}}$ gives the relation between electric field and distance. $$ \therefore E \propto \frac{1}{\left(\frac{r}{2}\right)^{3}} \Rightarrow E \propto \frac{8}{r^{3}} $$...
Force of attraction between two point electric charges placed at a distance d in a medium is . What distance apart should these be kept in the same medium, so that force between them becomes ?
Ans: If two point charges are $q_{1}$ and $q_{2}$ separated by distance $d$, it can be expressed as: $\mathrm{F}=\frac{\mathrm{Kq}_{1} \mathrm{q}_{2}}{\mathrm{~d}^{2}}$ Suppose if force becomes...
What is the work done in moving a point change from corner to corner of a square when a charge exists at the centre of the square?
Ans: Point $A \& B$ are at the same distance from the point $O$. Hence,
Why does the electric field inside a dielectric decrease when it is placed in an external electric field?
Ans: The electric field that is present inside a dielectric decreases when it is placed in an external electric field because of polarisation as it creates an internal electric field which is...
Electric charge is uniformly distributed on the surface of a spherical balloon. Show how electric intensity and electric potential vary
a) on the surface Ans: Electric field intensity on the surface of the balloon would be, $$ E=\frac{\sigma}{\varepsilon_{0}} $$ Electric potential on the surface of the balloon would be, $$ V=\frac{K...
A sphere 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...
A sphere 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...
Two charges 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...
A particle of mass 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, $$...