Question

In the circuit shown here, the ammeter A reads 5A and the voltmeter V reads 20V.The correct value of resistance R is

• A. exactly 4 ohm
• B. slightly greater than 4 ohm
• C. slightly less than 4 ohm
• D. 0

Answer 1

The correct option is B slightly greater than 4 ohm

Voltmeters generally have a high resistance

$\therefore$ Current$0A$ passes through

$I=0A$

$I_2+I_2=5A$

$\therefore I_1=5-I_2$

Also $I_2>0$ and $I_1<5$

Applying Ohm's law

$\frac{20}{5}<5(\because I_1=\frac{20}{R})\frac{20}{5}<R4<R\therefore R>4$

Current value of $R$ is slightly greater than $R$