Four cells, each of emf E and internal resistance r, are connected in series across an external resistance reverse. Then, the current in the external circuit is

Options

A. `(2E)/(4r+R)`
B. `(3E)/(4r+R)`
C. `(3E)/(3r+R)`
D. `(2E)/(3r+R)`

Answer

A

Explanation

Total emf of the cell = 3E - E = 2E

Total internal resistance = 4r
`therefore` Total resistance of the circuit = 4r + R
So, the current in the external circuit `" "(because i=(V)/(R ))`
`therefore " " i=(2E)/(4r+R)`