Question

Two points P and Q are maintained at the potentials of 10V and -4V respectively. The work done in moving 100 electrons from P to Q is

(a) –9.60 × 10^–17J 

(b) 9.60 × 10^–17J

(c) –2.24 × 10^–16J 

(d) 2.24 × 10^–16J

Answer 1

Work done in moving 100e^– from P to Q,
(Work done in moving 100 negative charges from the positive to the negative potential).
W = (100e^–)(V_Q^– V_P)
= (–100 × 1.6 × 10^–19)(–14V) = 2.24 × 10^–16J.