Question

An electric iron of resistance 20 ohm takes a current of 5 ampere calculate heat developed in 30 seconds

Answer 1

(R) = 20 Ω

(I)= 5 A

(t)= 30 s

Now we know that H= I2Rt

  

use it here     = 5×5×20×30

 = 15000J=1.5×104J

The heat developed in 30s is 1.5×104J

hope it may help you