Unit test ( Electrostatics) 2020

The dielectric constant of metals is

• 1

• Greater than 1

• Zero

• Infinite.

An electric dipole moment p is lying along a uniform electric  field  $\overrightarrow{E}$  . The work done in rotating the dipole by  $90\degree$  is:

•  pE

•  $\sqrt{2}$  pE

•  $\frac{\text{pE}}{2}$  

• 2pE

What is the angle between electric dipole moment and the electric field strength due to electric dipole on the equatorial line?

•  $0\degree$  

•  $90\degree$  

•  $180\degree$  

• None of these

The insulation property of air breakdown is E=3 X $10^6$ V/m. The maximum charge in coulomb that can be given to a sphere of diameter 5m is approximately:

• 2 X  $10^{-2}$  C

• 2X $10^{-3}$  C

• 2 X  $10^{-4}$  C

• 2 X  $10^{-5}$  C 

There is an electric field in the X - direction. If the work done in moving a charge of 0.2 C through a distance of 2m along a line making an angle of  $60\degree$  with X - axis is 4J, then what is the value of E?

•   $\sqrt{3}$  N/C

• 4 N/C

• 5 N/C

• 20 N/C

The electric field at a distance  $\frac{3R}{2}$  From the centre of a charged conducting spherical shell of radius R is E. The electric field at a distance  $\frac{R}{2}$  from the centre of the sphere is: 

• Zero

• E

•  $\frac{E}{2}$  

•  $\frac{E}{3}$  

A hollow cylinder has a charge q coulomb with it.  $\phi$  Is the electric flux in units of V/m associated with the curved surface B, the flux linked with the plane surface A in units of V m will be:

•  $\frac{\phi}{3}$  

•  $\frac{q}{2\in_0}$  

•  $\frac{1}{2}\left[\frac{q}{\in_0}-\phi\right]$  

•  $\frac{q}{\in_0}-\phi$  

The energy required to charge a parallel plate condenser of plate separation d and area of cross section A having the uniform electric field E between the plates is:

• $\frac{1}{2}\ \frac{\in_0E^2}{Ad}$

• $\in_0E^2Ad$

• $\frac{\in_0E^2}{Ad}$

• $\frac{1}{2}\in_0E^2Ad$

The charges are placed on the vertices of a square. Let E and V be the electric field and potential at the centre. If the charges at the points A and B are interchanged with those at D and C respectively. Then 

•  $\overrightarrow{E}$  remains unchanged, but V changes

• both  $\overrightarrow{E}$  And Vchange

• E and V remain unchanged.

• E changes and V remains unchanged.

The graph shows the variation of charge Q with potential V for two capacitors X and Y. In which capacitor more electrostatic energy is stored? (2)