Current refers to the flow of electric charge through a medium, while emf (electromotive force) is the energy per unit charge that is supplied by a source, such as a battery, to drive the flow of charge.
Current is typically measured in amperes (A) using a device called an ammeter, while emf is measured in volts (V) using a voltmeter.
According to Ohm's Law, the current in a circuit is directly proportional to the emf and inversely proportional to the resistance of the circuit. This relationship is expressed as I = emf/R, where I is current, emf is electromotive force, and R is resistance.
The direction of current flow is determined by the direction of the electric field, which is created by the emf. The positive terminal of a battery is typically considered the source of the electric field, and the current flows from the positive terminal to the negative terminal.
The magnitude of current depends on the emf and the resistance of the circuit. Higher emf or lower resistance will result in a larger current. The magnitude of emf can be affected by factors such as the type of battery or power source, the strength of the electric field, and the distance between the source and the conductor.