A current of 120 mA flows past a point in a circuit for 25 s.
How much charge passes the point in this time?
How many electrons pass the point in this time?
a) I = 120 mA = 120 x 10^(-3) A = 0.12 A = 0.12 C/s ... [b/c 1 A = 1 C/s] t = 25 s I = Q/t Q = It Q = 0.12 * 25 = 3 C so 3C of charge passes the point during the 25 s interval
