A charge Q is uniformly distributed over a long rod AB of length L as shown in the figure. The electric potential at the point O lying at a distance L from the end A is

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D.

A charged ball B hangs from a silk thread S which makes an angle θ with a large charged conducting sheet P, as shown in the figure. The surface charge density σ of the sheet is proportional to

• cos θ

• cot θ

• sin θ

• tan θ

D.

tan θ

A charged particle q is shot towards another charged particle Q which is fixed, with a speed v it approaches Q upto a closest distance r and then returns. If q were given a speed 2v, the closest distances of approach would be

• r

• 2r

• r/2

• r/4

A charged particle with charge q enters a region of constant, uniform and mutually orthogonal fields , with a velocity perpendicular to both  , and comes out without any change in magnitude or direction of  .Then

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A.

A long cylindrical shell carries positive surface charge  in the upper half and negative surface charge  in the lower half. The electric field lines around the cylinder will look like figure given in: (figures are schematic and not drawn to scale)

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D.

Field lines should originate from a positive charge and terminate negative charge.