Question

In the circuit shown the readings of ammeter and voltmeter are $4\text{A}$ and $20\text{V}$ respectively. The meters are non-ideal, then $R$ is :

• A. $5\Omega$
• B. less than $5\Omega$
• C. greater than $5\Omega$
• D. between $4\Omega \&5\Omega$

Answer 1

The correct option is C greater than $5\Omega$

Given:
$i=4\text{A};V=20\text{V}$


From diagram,

$R=\frac{V}{i_1}=\frac{20}{i_1}$

$\Rightarrow i_1=\frac{20}{R}$

Since, voltmeter is non- ideal, so some current will also passes through it.

$\therefore i_1<4\text{A}$

$\frac{20}{R}<4\Rightarrow R>5\Omega$

Hence, option $\left(c\right)$ is the correct answer.