Question

An electric iron of reaistance 20r takes a current 5A.Calculate the heat developed in 30s​

Answer 1

Answer:

1500J

Explanation:

H=I*2XRXT

H=5*2X20X30

H=25X20X30

H=15000J

Answer 2

According to Joule's law of heating, the amount of heat produced is given by

H = VIt

where,

V = IR = 5A × 20 $\Omega$ = 100V

I = 5A

and t = 30seconds

So,

H = 100×5×30J

= 15000J

= $\small\sf{1.5×{10}^{4}J}$