Question

A student's $9.0V,7.5W$ portable radio was left on from $9:00P.M.$ until $3:00A.M.$ How much charge passed through the wires?

• A. $18000C$
• B. $24000C$
• C. $6000C$
• D. $12000C$

Answer 1

The correct option is A $18000C$

As we know,
Power, $P=V\cdot I$
$I=\frac{P}{V}$
$\Rightarrow I=\frac{Q}{t}=\frac{P}{V}$
$\Rightarrow Q=\frac{P}{V}\times t=\frac{7.5}{9}\times 3600\times 6$
$=18000C$
$[\because t=9PM$ to $3AM=6hr=6\times 3600s]$