An electric dipole is situated in an electric field of uniform intensity E whose dipole moment is p and moment of inertia is I. If the dipole is displaced slightly from the equilibrium position, then the angular frequency of its oscillations is 

(1) ${\left(\frac{{\displaystyle pE}}{{\displaystyle I}}\right)}^{1/2}$

(2) ${\left(\frac{{\displaystyle pE}}{{\displaystyle I}}\right)}^{3/2}$

(3) ${\left(\frac{{\displaystyle I}}{{\displaystyle pE}}\right)}^{1/2}$

(4) ${\left(\frac{{\displaystyle p}}{{\displaystyle IE}}\right)}^{1/2}$

The electric field due to a uniformly charged sphere of radius R as a function of the distance from its centre is represented graphically by 

(1)  (2)

(3)  (4)

Suppose the charge of a proton and an electron differ slightly. One of them is -e and the other is $\left(e+∆e\right)$. If the net of electrostatic force and gravitaional force between two hydrogen atoms placed at a distance d (much greater than atomic size) apart is zero,then $∆e$ is of the order [Given mass of hydrogen, $m_h$=1.67$\times {10}^{-27}$ kg]

(a) ${10}^{-20}C$

(b)${10}^{-23}C$

(c) ${10}^{-37}C$

(d) ${10}^{-47}C$

An electric dipole is place at an angle of ${30}^{\circ }$ with an electric field intensity 2$\times {10}^5$ N/C. It experiences a torque equal to 4 Nm. The charge on the dipole, if the dipole length is 2 cm, is

(a) 8 mC              (b) 2 mC

(c) 5 mC              (d) 7 $\mu$C 

Two identical charged spheres suspended from a common point by two massless strings of lengths l are initially at a distance d(d < < l) apart because of their mutual repulsion. The charges begin to leak from both the spheres at a constant rate. As a result, the spheres approach each other with a velocity v. Then, v varies as a function of the distance x between the sphere, as

(a)$v \alpha x$ 

(b)$v \alpha x^{\frac{-1}{2}}$

(c)$v \alpha x^{-1}$

(d)$v \alpha x^{\frac{1}{2}}$

 

The electric field in a certain region is acting radially outward and is given by E=Ar. A charge contained in a sphere of radius 'a' centered at the origin of the field will be given by

1. $4\pi {\in }_{o}A{a}^2$

2. $\pi {\in }_{o}A{a}^2$

3. $4\pi {\in }_{o}A{a}^3$

4. ${\in }_{o}A{a}^2$

What is the flux through a cube of side a if a point charge of q is a one of its corner?

1. $\frac{2q}{{\epsilon }_0}$                                         

2. $\frac{q}{8{\epsilon }_0}$

3. $\frac{q}{{\epsilon }_0}$                                         

4. $\frac{q}{2{\epsilon }_0}6a^2$

A charge Q is enclosed by a Gaussian spherical surface of radius R. If the radius is doubled, then the outward electric flux will

1. be reduced to half                                 

2. remain the same

3. be doubled

4. increase four times

Two positive ions, each carrying a charge q, are separated by a distance d. If F is the force of repulsion between the ions, the number of electrons missing from each ion will be (e being the charge on an electron)

1. $\frac{4{\mathrm{\pi \epsilon }}_{\circ }{\mathrm{Fd}}^2 }{e^2}$                  2. $\sqrt{\frac{4{\mathrm{\pi \epsilon }}_{\circ }{\mathrm{Fe}}^2}{d^2}}$

3. $\sqrt{\frac{4{\mathrm{\pi \epsilon }}_{\circ }{\mathrm{Fd}}^2}{e^2}}$               4. $\frac{4{\mathrm{\pi \epsilon }}_{\circ }{\mathrm{Fd}}^2}{q^2}$