Question

A 120-V potential difference is applied across a 100 Ω resistor. What is the current in mA that flows into the resistor?

Answer 1

Given potential difference V = 100volts,

Resistance of the resistor, R = 50ohms.

So power produced in the circuit , P =(V^2)/R

i.e. P = 100*100/50 = 200 watt = 200 J/s.

But we know, P = energy/ time

So, energy = power * time

Time should be taken in it's standard units i.e seconds

6min 58 seconds = (6*60)+58 = 418 seconds.

Energy = (200 *418)J = 83,600J

We know that 1calorie = 4.184J

So, energy= (83,600)/4.184 = 19,980.87 calories.

Final answer :-(1) energy = 83,600 J

(2) energy = 19,980.87 calories.