electric potential

The expression for Electric potential due to a point charge at a distance 'r' from it is____________

• $\frac{1}{4\pi\epsilon\ _{0\ }}\ \frac{q^{2\ }}{r}$

• $\frac{1}{4\pi\epsilon\ _{0\ }}\ \frac{q}{r}$

• $\frac{1}{4\pi\epsilon\ _{0\ }}\ \frac{q^{2\ }}{r^2}$

• $\frac{1}{4\pi\epsilon\ _{0\ }}\ \frac{q\ }{r^2}$

Electric potential energy of an electric dipole in a uniform electric field is given by

• 
  

  $U=\overrightarrow{p\ }\times\overrightarrow{E}$
  

• $U=\overrightarrow{E}\times\overrightarrow{p}$

• $U=-\overrightarrow{p\ }.\overrightarrow{E}$

• $U=-\frac{\left(\overrightarrow{p\ }.\overrightarrow{\ E\ }\right)}{\epsilon_o}$

How is the capacitance (C) of a parallel-plate capacitor affected by the charge on the plates ?

• C depend on the charge on the plates

• C is vanished when there are plates

• C does not depend on the charge on the plates

• C is accumulated on one side only

Is there a limit to the amount of charge that capacitor can hold and why/why not?

• Yes, as the ratio of charge to p.d. is fixed.

• Yes, because the dielectric will breakdown in such a large field and charge will remain.

• No, as capacitance can always increase as p.d. increases.

• Yes, because the dielectric will breakdown in such a large field and charge will flow.

Two charges +q and -3q are placed at a distance of 1m apart. The points on the line joining two charges, where electric potential is zero, is :

• 0.25 m, 0.5 m

• 1 cm , 0.50 m

• 0.35 cm , 24 cm

• none of these

Electric field and electric potential inside a charged spherical shell :

• E = 0; V = 0

• E = 0 ; V ≠ 0

• E ≠ 0 ; V = 0

• E ≠ 0 ; V ≠ 0

An electron is accelerated under a potential difference of 182 V. The maximum velocity of electron will be -------. Mass of electron = 9.1 x 10^-31 kg.

• 5.65 x 10⁶ m/s

• 4 x 10⁶ m/s

• 8 x 10⁶ m/s

• 16 x 10⁶ m/s

As a proton moves in the direction the electric field lines...

• it is moving from low potential to high potential and gaining electric potential energy.
• it is moving from low potential to high potential and losing electric potential energy.
• it is moving from high potential to low potential and gaining electric potential energy.
• it is moving from high potential to low potential and losing electric potential energy.

Potential energy of an electric dipole held at an angle  $\theta$   in a uniform electric field is zero ,,when  $\theta$   is

•  $0^{\degree}$  

•  $90^{\degree}$  

•  $180^{\degree}$  

•  $360^{\degree}$  

Consider the following statements:

Statement 1: The equipotential surface at a point is always normal to the electric field at that point. Statement 2: If the electric field were not normal to the equipotential surface, work has to be done in moving a test charge on the surface.

• Both statements are correct and Statement 2 is the correct explanation for the Statement 1.

• Both statements are correct and Statement 2 is not the correct explanation for the Statement 1.

• Statements 1 is correct and Statement 2 is wrong

• Statements 1 is wrong and Statement 2 is correct