When a car's starter is in use, it draws a large current. The car's lights draw much less current. As a certain car is starting, the current through the battery is 60.0 A and the potential difference across the battery terminals is 9.00 V. When only car's lights are used, the current through the battery is 2.00 A and the terminal potential difference is 11.9 V.
a) Find the battery's emf?
b) What is its internal resistance?