100 cells each of emf 5V and internal resistance `1 Omega` are to be arranged to produce maximum current in a `25 Omega` resistance. Each row contains equal number of cells. Find the number of rows.

Options

A. 2
B. 3
C. 50
D. 40

Answer

A

Explanation

Let n be the number of cells in a row and m be the number of rows.
Now, maximum current is obtained for `r=R`. In mixed combination total resistance of the circuit is given by,
`R=(nr)/(m) :.25(n)/(m) r :. (n)/(m)=25`
`:.n=25m` ....(i)
In mixed combination, we have,
`nm=100` ...(ii)
From equation (i) and (ii) we have,
`mxx25m=100`
`25m^(2)=100`
`m^(2)=4:.m=2 ` and `n=50`