Question

In the given circuit the power generated in $5\Omega$ resistance will be maximum for $x$ equal to

• A. $1\Omega$
• B. $7\Omega$
• C. $\frac{2}{3}\Omega$
• D. $0\Omega$

Answer 1

The correct option is D $0\Omega$

From given diagram, equivalent resistance of circuit will be

$R_{eq}=2+5+x=(7+x)\Omega$

So, current in the circuit is given by

$i=\frac{E}{7+x}$

Power generated in $5\Omega$ is

$P=i^{2}R={\left(\frac{E}{7+x}\right)}^2\times 5=5{\left(\frac{E}{7+x}\right)}^2$

Power will be maximum when $(7+x)$ is minimum i.e. for $x=0$.

Hence, option $\left(d\right)$ is correct.