Question

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

Answer 1

Hint
We should know that heat is defined as energy in transfer to or from a thermodynamic system, by mechanisms other than thermodynamic work or transfer of matter. The various mechanisms of the energy transfer that define the heat. Based on this concept we have to solve this question.

Complete step by step answer
We know that:
Heat is given as:
$H = {I^2}Rt = {5^2} \times 20 \times 30$
$H= 15000$
Here $H$ is the heat, $I$ is the current, $R$ is the resistance and $t$ is the time.

Hence, the answer is 15000 J.

Note
It should be known that heat energy or thermal energy gives us an idea about the energy of the object that is obtained due to the movement of its molecules and also heat can be transferred from one object to another object. There are 3 ways by which heat is transferred between the substances. They are conduction, convection and radiation.