(1) A circular ring of radius r made of a nonconducting material is placed with its axis parallel to a uniform electric field. The ring is rotated about a diameter through 180 degree. Does the flux of electric field change? If yes, does it increase or decrease and why?

 

(2) A change Q is uniformly distributed on a thin spherical shell. What is the field at the centre of the shell? If a point charge is brought close to the shell, will the field at the centre change? Does the answer depend on whether the shell is conducting or nonconducting?

 

(3) A spherical shell made of plastic, contains a charge Q distributed uniformly over its surface. What is the electric field inside the shell? If the shell is hammered to deshape it without altering the charge, will the field inside be changed? What happens is the shell is made of metal?

Q1. I guess the flux will not change if the ring is rotated about a diameter through 180 degree. because

flux =   Edscos 

though you rotate by 180 the angle made by the area vector to the field remains 0. they are parallel.

 

2) the field at the centre of the shell or any conductor is always 0.

 if it is conductor. the field will not change if another charge is brought near it.

Electrostatic shielding.

 

 I guess this question and the next have already been discussed. Do search.

 

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