Question

A battery having 12V emf and internal resistance `3Omega` is connected to a resistor. If the current in the circuit is 1A, then the resistance of resistor and lost voltage of the battery when circuit is closed will be
A. `7Omega,7V`
B. `8Omega,8V`
C. `9Omega,9V`
D. `9Omega,10V`

Answer 1

Correct Answer - C
Here, `epsi=12V, r=3Omega, I=1A,V=IR=epsi-Ir`
`therefore R=(epsi-Ir)/(I)=(12-1xx3)/(1)=12-3=9Omega`
and `V=IR=1xx9=9V`