A clock battery wears out after moving 10,400 C of charge through the clock at a rate of 0.530 mA. (a) How long (in s) did the clock run? s (b) How many electrons per second flowed?

Explanation:

Given that:

Charge Q = 10400 C

current I = 0.530 mA

From our previous knowledge, we know that charge Q can be expressed as:

Q = I×t

where

I = current and t = time

∴

replacing our values

10400 = (0.530×10⁻³) t

t = 10400/(0.530×10⁻³)

t = 19622641.51 seconds

However, the required flow of electrons per seconds can be calculated by using the formula:

number of electrons/second = current (I)/ charge on electron

= (0.530×10⁻³)/(1.6×10⁻¹⁹)

= 3.3125×10¹⁵ electrons