Question

Two resistors $400 \,\Omega$ and $800\,\Omega$ are connected in series with a $6 \,V$ battery. The potential difference measured by voltmeter of $10 \,k$ ? across $400 \,\Omega$ resistor is

• A. 2 V
• B. 1.95 V
• C. 3.8 V
• D. 4 V

Answer 1

Answer: (B)

Here, the resistances of $ 400\,\Omega $ and $ 10000\,\Omega $ are in
parallel, their effective resistance $ {{R}_{P}} $ will be
$ {{R}_{P}}=\frac{400\times 10000}{400+10000} $
$ =\frac{5000}{13}\Omega $
Total resistance of the circuit,
$ =\frac{5000}{13}+800=\frac{15400}{13}\Omega $
Current in the circuit
$ i=\frac{6}{15400/13}=\frac{39}{7700}A $
Potential difference across voltmeter
$ =i{{R}_{P}} $
$ =\frac{39}{7700}\times \frac{5000}{13}=1.95\,V $