Question

When a high resistance voltmeter is connected directly across a resister its reading is 2 V. An electric cell is sending the current of 0.4A, (measured by an ammeter) in the electric circuit in which a rheostat is also connected to vary the current.

Find the resistance of the resister.

Answer 1

Since the voltmeter reading shows 2V. Thus V = 2.

Also, Current send by electric cell = 0.4A 

Thus I = 0.4A 

By Ohm’s law V = IR 

⇒ 2 = 0.4 × R 

⇒ R = \(\frac{2}{0.4}=\frac{20}{4}\) = 5Ω

The resistance of the resistor is 5Ω.