Question

A battery of internal resistance $4\,\Omega$ is connected to the network of resistances as shown in figure. In order that the maximum power can be delivered to the network, the value of $R$ should be

• A. $\frac{4}{9}$ $\Omega$
• B. $\frac{8}{3}\Omega$
• C. $18\Omega$
• D. $2\Omega$

Answer 1

Answer: (D)

The given circuit is a balanced Wheatstone's bridge.

Thus, no current will flow across $6R$ of the side CD. The given circuit will now be equivalent to


For maximum power, net external resistance
= Total internal resistance
or $2R=4$
or $R=2\,\Omega .$