4. What is meant by an emf device? What are the units of emf? What is meant by the internalresistance of a battery? Explain the distinction between an ideal emf

device and a real emfdevice. Describe the relation between the terminal voltage and emf of a battery. Describethe rules for combining resistors in series and in parallel. Explain the "Loop Rule" and the“Junction Rule." Show an example of how to use them to analyze a circuit.