Question

100 cells each of e.m.f. 5 V and internal resistance 1 ohm are to be arranged so as to produce maximum current in a 25 ohms resistance. Each row is to contain equal number of cells. The number of rows should be

• A. 2
• B. 4
• C. 5
• D. 10

Answer 1

Answer: (A)

2

Answer 2

If m = Number of rows

and n = Number of cells in a row

Then m × n = 100 .....(i)

Also condition of maximum current is $R = \frac { n r } { m }$

⇒ $25 = \frac { 1 \times n } { m }$ ⇒ n = 25 m .....(ii)

On solving (i) and (ii) m = 2