In a particular television picture tube, the measured beam current is 59 µA.?

Question

How many electrons strike the screen every second?

Answer 1

This is a simple question.

The electric current i is defined as i = q/t, where q is the electric charge that pass at the certain cross-section in time t. Then, we have to know that electric charge in this case is carried by electrons. The single electron carries so called elementary charge, denoted e, e = 1.602 × 10–19 C. Let's say we have N electrons in charge q, which gives q = Ne and i = Ne/t. We solve for N:

N = it/e = 59 × 10–6 A × 1 s / × 1.602 × 10–19 As  = 3.7 E 14.