Question

For the electrical circuit shown in the figure, the potential difference across the resistor of 400Ω as will be measured by the voltmeter V of resistance 400 is …….. 

(A) (10 / 3)V 

(B) 4V 

(C) (20 / 3)V 

(D) 5V

Answer 1

The correct option is (C) (20 / 3)V.

Explanation:

∵ Voltmeter has resistance 400Ω, and is in parallel with 400Ω. 

∴ Circuit reduces to

∴ The circuit is balanced wheatstone bridge. 

∴ O current through BC 

i = Current through arm BD = [(10) / (100 + 200)] = [(10) / (300)]A 

∴ Potential across 400Ω = Potential across arm BD = reading of voltmeter 

∴ Potential difference = i × 200 

= [10 / (300)] × 200 = (20 / 3)V