A $7.0 - \Omega$ Resistor Is Connected Across the Terminals of a Battery Having

Multiple Choice

A $7.0 - \Omega$ resistor is connected across the terminals of a battery having an internal emf of $10 \mathrm {~V}$ . If $0.50 - \mathrm { A }$ current flows, what is the internal resistance of the battery?

A) $20 \Omega$
B) $13 \Omega$
C) $27.0 \Omega$
D) $10.8 \Omega$