Question

The potential difference between the terminal of an electric heater is 60v wjen it draws current of 4À from the source. What current will the heater draw if the potential difference increased 12v ?

Answer 1

resistance in both cases are same .
due to no any change of substance used in heater . so, resistance is same .

now, use Ohm's law ,

V = iR
given,
V = 60 volt
I = 4 Ampere

R = 60/4 = 15 ohm

now,

again , use Ohm's law for second case
V = iR
i = V/R
here ,

V= 72V
R = 15 ohm

so, i = 72/15 = 24/5 = 4.8 Ampere

Answer 2

V is proportional to I

V varies as I varies.But Resistance (R) remains constant.

So using the Ohm's Law,
V = IR

Given P.D = 60 v
Current = 4 A
R = V/I
R = 60/4 = 15 ohm

Now we have P.D is increased by 12 v so new V = 12 + 60 = 72 v
R = 15 ohm

I = V/R
I = 72/15 = 4.8 A

In Short Your Answer will be : 4.8 A

Hope This This.