Two identical cells whether connected in parallel or in series gives the same current, when connected to an external resistance `1.5Omega`. Find the value of internal resistance of each cell.

Options

A. `1Omega`
B. `0.5Omega`
C. Zero
D. `1.5Omega`

Answer

D

Explanation

Given, n = 2, m = 2
`R = 1.5 Omega`
Let n cells e in series and m in parallel gives the same current, then
`(nE)/(R+nr)=(E )/(R+(r )/(m))`
`rArr " " n[R+(r )/(m)]=R + nr`
`rArr nRm+nr=Rm+mnr`
`rArr 6+2r=3+4r`
`rArr 2r=3 rArr r=1.5 Omega`