Five Styrofoam balls are suspended from insulating threads. Several experiments are performed on the balls and the following observations are made:
(i) Ball A repels C and attracts B.
(ii) Ball D attracts B and has no effect on E.
(iii) A negatively charged rod attracts both A and E.
An electrically neutral Styrofoam ball gets attracted if placed nearby a charged body due to induced charge. What are the charges, if any, on each ball?

Options

A. `{:(A,B,C,D,E),(+,-,+,0,+):}`
B. `{:(A,B,C,D,E),(+,-,+,+,0):}`
C. `{:(A,B,C,D,E),(+,-,+,0,0):}`
D. `{:(A,B,C,D,E),(-,+,-,-,0):}`

Answer

C

Explanation

From (i), as A repels C, so both a and C must be charged similarly. Either both are +ve or both are -ve. As A also attract B, so charge on B should be opposite of A or B may be uncharged conductor.
From (ii) as D has no effect on E, so both D and E should be should be uncharged and as B attracts unchraged D, so B must be charged and D must be an uncharged conductor.
From (iii), a -vely charged rod attracts the charged ball A, so A must be +ve and from exp. (i) C must also be +ve and B must be -ve.