Question

An electric iron of resistance $20\Omega$ takes a current of $5A$. Calculate the heat developed in $30seconds$.

• A. $1.5\times {10}^{4}J$
• B. $2.8\times {10}^{4}J$
• C. $2.5\times {10}^{5}J$
• D. $2.5\times {10}^{4}J$

Answer 1

The correct option is A

$1.5\times {10}^{4}J$

Given, Current, $I=5A$; Time, $t=30s$; Resistance, $R=20\Omega$

The amount of heat (H) produced is given by $H=I^{2}Rt$ Where I is the current, R is the resistance and t is the time interval.

$H=I^{2}Rt$

$H=5^2\times 20\times 30$

$H=1.5\times {10}^{4}J$
Therefore, the amount of heat developed in the electric iron is $1.5\times {10}^{4}J$.