Question

The energy expended in $1kW$ electric heater in $30\text{seconds}$ will be:

• A. $3\times {10}^{4}J$
• B. $3\times {10}^{4}erg$
• C. $3\times {10}^{4}eV$
• D. $0$

Answer 1

Answer: (A)

$3\times {10}^{4}J$

$\text{Energy = Power}\times \text{time}$

$Power=1kW=1000W$ and $time=30s$
$\text{Energy}=1000\times 30=30000J=3\times {10}^{4}J$