Three identical cells , each having an `emf 1.5 V` and a constant internal resistance `2.0 ohm`, are connected in series with a `4.0 ohm` resistor R, first as in circuit (i) , and second as in circuit (ii) . Then
( power in R in circuit (i))/( Power in R in circuit (ii)) =

Options

A. `9.0`
B. `7.2`
C. `1.8`
D. `3.0`

Answer

A

Explanation

Power `P = I^(2)R = ((V)/( R + 3 r ))^(2) R or P prop V^(2)`
Power ratio `= ((V_(1))/(V_(2)))^(2) = (( 4.5)/( 1.5))^(2) = 3^(2) = 9 `