The `n` rows each containing `m` cells in series are joined parallel. Maximum current is taken from this combination across an external resistance of `3 Omega` resistance. If the total number of cells used are 24 and internal resistance of each cell is `0.5 Omega` then

Options

A. m=8, n=3
B. m=6, n=4
C. m=12, n=2
D. m=2, n= 12

Answer

C

Explanation

`n to` rows, m `to` cell in each now
`R = 3Omega, m xx n = 24`
`R = (mr)/n rArr 3 = (m xx 0.5)/n rArr 3n = 0.5 m rArr m = 6n`
`6n xx n = 24 rArr n =2, m=12`