Question

Consider all possible values of $R$ in the circuit shown. Then, the maximum possible rate at which energy can be supplied by the ideal battery to the given combination of resistors is equal to,

• A. $10W$
• B. $13.3W$
• C. $16W$
• D. $20W$

Answer 1

Answer: (D)

So, here we want the power delivered by battery to be maximum.
Power delivered by battery $\left(V\right)$ to resistance $\left(R\right)$ ,
$P=\frac{V^2}{R}$ .
So, for a given battery, if $R$ is minimum, then $P$ is maximum.
So, here,

if $R=0$ , then equivalent resistance of circuit is minimum, so $10\Omega$ .
It would be short-circuited. So, equivalent resistance of circuit, $R_{eq}=20\Omega$ .
$P=\frac{(20{)}^2}{(20)}=20W$