Question

21. A current of 2 A produces 200 J of heat in a wire in a
given period of time. If the current is increased to
4 A, how much heat will be produced in the same
time?​

Answer 1

I = 2A

Heat = 200J

Using Joules law of heating

H = I²Rt

200 = ( 2² ) ( R ) ( t )

200 = 4 Rt

200/4 = Rt

50 = Rt

t = 50/R – ( 1 )

Now if current is increased to 4A

I' = 4A

H' = I'² Rt

H' = ( 4 )² R t

H' = 16 R ( 50/ R ) { Value of t from 1 }

H' = 16 × 50

H' = 800 Joules