ELECTROSTATICS ( TN +2 )

Two identical point charges of magnitude –q are fixed as shown in the figure below. A third charge +q is placed midway between the two charges at the point P. Suppose this charge +q is displaced a small distance from the point P in the directions indicated by the arrows, in which direction(s) will +q be stable with respect to the displacement?

• A₁ and A₂

• B₁ and B₂

• both directions

• No stable

Which charge configuration produces a uniform electric field?

• point charge

• uniformly charged infinite line

• uniformly charged infinite plane

• uniformly charged spherical shell

What is the ratio of the charges $\frac{\left|q_1\right|}{\left|q_2\right|}$    for the following electric field line pattern?

• 1/5

• 25/11

• 5 

• 11/25

An electric dipole is placed at an alignment angle of 30^o with an electric field of 2 × 10⁵ NC^–1. It experiences a torque equal to 8 Nm. The charge on the dipole if the dipole length is 1 cm is

• 4 mC

• 8 mC

• 5 mC

• 7 mC

Four Gaussian surfaces are given below with charges inside each Gaussian surface. Rank the electric flux through each Gaussian surface in increasing order.

• D < C < B < A

• A < B = C < D

• C < A = B < D

• D > C > B > A

The total electric flux for the following closed surface which is kept inside water

• $\frac{80q}{\epsilon_0}$

• $\frac{q}{40\epsilon_0}$

• $\frac{q}{80\epsilon_0}$

• $\frac{q}{160\epsilon_0}$

Two identical conducting balls having positive charges q₁ and q₂ are separated by a centre to centre distance r. If they are made to touch each other and then separated to the same distance, the force between them will be

• less than before

• same as before

• more than before

• zero

Rank the electrostatic potential energies for the given system of charges in increasing order.

• 1 = 4 < 2 < 3

• 2 = 4 < 3 < 1

• 2 = 3 < 1 < 4

• 3 < 1 < 2 < 4

An electric field   $\overrightarrow{E\ }\ =10x\ i^{\wedge}$   exists in a certain region of space. Then the potential difference $V=\ V_0-V_A$  , where  $V_0$  is the potential at the origin and VA is the potential at x = 2 m is:

• 10 V  

• –20 V

• +20 V

• –10 V

A thin conducting spherical shell of radius R has a charge Q which is uniformly distributed on its surface. The correct plot for electrostatic potential due to this spherical shell is

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