Electrical Machine

1. What is the reason that the terminal voltage is less than emf?

EMF is the potential difference across the two terminals of a voltage source when it is not connected to any circuit. Once it is connected to a circuit, the voltage reduces slightly because of the internal resistance of the voltage source. The terminal voltage of the voltage source is the potential difference across the terminals when it is connected to a circuit. Thus V is always less than E. This can also be observed from the following eqn: V=E-Ir.