When a battery connected across a resistor of `16Omega` , the voltage across the resistor is 12 V. When the same battery is connected across the resistor of `10Omega` voltage across it is 11 V. The internal resistance of the battery in ohm is

Options

A. `(10)/(7)`
B. `(20)/(7)`
C. `(25)/(7)`
D. `(30)/(7)`

Answer

C

Explanation

Form the figure,
Current across the arms ,P`RQ = 1A`
ans `PSQ = 1A`
`Also , V_P- V_R = 3V`
`V_p - V_S = 7V`
From equation (1) and (2) , we get ,
`V_r-V_3 = 7-3 = 4V`