Two identical calls send the same current in `2 Omega` resistance, whether connected in series or in parallel. The internal resistance of the cell should be

Options

A. `1Omega`
B. `2Omega`
C. `0.5Omega`
D. `2.5Omega`

Answer

B

Explanation

In series, `I_(1)=(E )/(1+r)`
In parallel `I_(2)=(E )/(2+(r )/(2)) =(2E)/(4+r )`
Since `I_(1)=I_(2) rArr (E )/(1+r )=(2E )/(4+2r) rArr r=2Omega`