A battery of internal resistance `4 Omega` is connected to he network of resistances as shown in Fig. `7.40`. In order that the maximum power can be delivered to the network , the value of `R` in ` Omega` should be

Options

A. `4//9`
B. `8//9`
C. 2
D. 18

Answer

C

Explanation

The equivalent circuit becomes a balanced wheatstone bridge
For maximum power transfer,external resistance should be equal to internal resistance of source
`rArr`  `((R+2R)(2R+4R))/((R+2R)(2R+4R))`=4i.s. `(3Rxx6R)/(3Rxx6R)`=4 or r=`2Omega`