A voltmeter of resistance 600 Ω is used to measure the potential drop across 300 Ω resistor. The measured value of potential drop will be

50 V

The correct answer is Option (1) → 50 V

Effective resistance across 300 Ω with voltmeter (600 Ω in parallel):

$R_{eq}=\frac{300 \times 600}{300+600}=\frac{180000}{900}=200 \ \Omega$

Total resistance in circuit: $R_{tot}=200+200=400 \ \Omega$

Current in circuit: $I=\frac{100}{400}=0.25 \ \text{A}$

Potential drop across parallel branch (i.e. measured by voltmeter):

$V=I \times 200=0.25 \times 200=50 \ \text{V}$

Answer: The measured potential drop = $50 \ \text{V}$