An electric iron of resistance 20 ohm takes a current of 5 A. Calculate the heat developed in 30 s.

Explanation

Here, current I = 5 A,
resistance R = 20 `Omega`, time t = 30 s
Now,
Heat produced `H = I^2Rt`
`= (5)^2 xx 20 xx 30`
` = 25 xx 20 xx 30`
`= 15000 J`
` =15 kJ`