Question

Practice 1. If the current in a wire of a CD player is 5.00 mA, how long would it take for 2.00 C of charge to pass through a cross-sectional area of this wire?

Answer 1

Answer:

$T=4\times10^2s$

Explanation: The time needed for the 2.00C charge to pass at a current of 5.00mA is:

$I=5.00mA=5.00\times10^{-3}\rightarrow I=5.00\times10^{-3}\frac{C}{s}$

Therefore time is:

$\begin{gathered} T=\frac{Q}{I}=\frac{2C}{(5.00\times10^{-3}\frac{C}{s})}=\frac{2}{5}\times10^3s \\ \therefore\Rightarrow \\ T=0.4\times10^3s=4\times10^2s \\ T=4\times10^2s \end{gathered}$

Note! Q is for charge and I is for current