Electrostatics 7 Question 15

15. Two identical thin rings, each of radius R, are coaxially placed a distance R apart. If Q1 and Q2 are respectively the charges uniformly spread on the two rings, the work done in moving a charge q from the centre of one ring to that of the other is

(1992, 2M)

(a) zero

(b) q(Q1Q2)(21)2(4πε0R)

(c) q2(Q1+Q2)(4πε0R)

(d) q(Q1/Q2)(2+1)2(4πε0R)

Show Answer

Answer:

Correct Answer: 15. (b)

Solution:

  1. VC1=VQ1+VQ2=14πε0Q1R+14πε0Q2R2

=14πε0RQ1+Q22

Similarly VC2=14πε0RQ2+Q12

ΔV=VC1VC2=14πε0R(Q1Q2)12(Q1Q2)

=Q1Q22(4πε0R)(21)W=qΔV=q(Q1Q2)(21)/2(4πε0R)



NCERT Chapter Video Solution

Dual Pane