Question

In the adjoining circuit, the e.m.f. of the cell is 2 volt and the internal resistance is negligible. The resistance of the voltmeter is `80 ohm`. The reading of the voltmeter will be

A. 0.80 volt
B. 1.60 volt
C. 1.33 volt
D. 2.00 volt

Answer 1

Correct Answer - C
(c ) Total resistance of the circuit `= (80)/(2) + 20 = 60 Omega`
`implies` Main current `i= (2)/(60) = (1)/(30)`
Combination of voltmeter and `80 Omega` resistance is connected in series with `20 Omega`, so current through `20 Omega` and this combination will be same `= (1)/(30) A`.
Since the resistance of voltmeter is also `80 Omega`, so this current is equally distributed in `80 Omega` resistance and voltmeter (i.e., `1//60 A` through each).
`P.D.` across `80 Omega` ressitance `= (1)/(60) xx 80 = 1.33 V`