Question

A candidate connect a moving coil voltmeter V, a moving coil ammeter A, and a resistor R as shown in figure. If the voltmeter reads 20 V and the ammeter reads 4A, R is

• A. equal to 5 $\omega$
• B. greater than 5 $\omega$
• C. less than 5 $\omega$
• D. greater or less than 5 $\omega$ depending upon its material

Answer 1

The correct option is B greater than 5 $\omega$

Let a current of $x$ ampere pass through the voltmeter; then $(4-x)$
ampere passes through the resistance R. Therefore, voltmeter reading is

$20=(4-x)R,$ i.e., $R=\frac{20}{4-x}$, i.e., $R>5\omega$