Question

a) A total charge of 72 Coulombs is transmitted by a silver wire 1.5 mm in a diameter over a time of 1 hour and 30 minutes. What is the current and it’s density in the wire?

Answer 1

Explanations & Calculations.

• The total time is 90 minutes.

1)

• Use Q = it

$\qquad\qquad \begin{aligned} \small i&=\small \frac{72\,C}{90\times60\,s}\\ &=\small 0.01\,A\\ &=\small 10\,mA \end{aligned}$

2)

• Current density

$\qquad\qquad \begin{aligned} \small \text{CD}&=\small \frac{i}{\text{Area}}\\ &=\small \frac{0.01\,A}{\pi(0.75\times10^{-3}\,m)^2}\\ &=\small 5658.8\,Am^{-1} \end{aligned}$