Question

State joules law and write the mathematical formula of joules law.
Calculate the heat developed in 30 s, if an electric iron of resistance 20ohm
take a current of 5 A.​

Answer 1

Joule's law :

Explanation:

The joule’s law shows the between heat created by flowing electrical phenomenon through a conductor.

Joule's law of heating states that the power of heating generated by an electrical conductor is proportional to the product of its resistance (R) and the square of the electric current passing through the conductor with time.

∴  Q =$I^2$ RT

where

Q = amount of heat

I = electric current

R = electric resistance in the conductor

T =  time

Now, given that

T = 30 s

R = 20 Ω

I = 5 A

Q =?

According to Joule's law,

Q = $I^2$ RT

    = 5 × 5 × 20 ×30

Q = 15000 J

Q = 15 KJ