Question

(a) Write down the formula which relates electric charge, time and electric current
(b) A radio set draws a current of 0.36 A for 15 minutes. Calculate the amount of electric charge that flows through the circuit.

Answer 1

(a) If a charge of Q coulombs flows through a conductor in time t seconds, the magnitude, I of the electric current flowing through it is given by:
$I\mathit{=}\frac{\mathit{Q}}{\mathit{t}}$
(b) Given:
Current, I = 0.36 A
Time, t = 15 minutes = (15 $\times$ 60) s = 900 s
Using the formula, $I\mathit{=}\frac{\mathit{Q}}{\mathit{t}}$:
or Q = I $\times$ t = 0.36 $\times$ 900 = 324 C
Thus, the amount of electric charge that flows through the circuit is 324 C.