Inductance is the property in an electrical circuit where a change in the electric current through that circuit induces an electromotive force (EMF) that opposes the change in current.In electrical circuits, any electric current i produces a magnetic field and hence generates a total magnetic flux Φ acting on the circuit. This magnetic flux, due to Lenz's law, tends to act to oppose changes in the flux by generating a voltage (a back EMF) in the circuit that counters or tends to reduce the rate of change in the current. The ratio of the magnetic flux to the current is called the self-inductance, which is usually simply referred to as the inductance of the circuit. To add inductance to a circuit, electronic components called inductors are used, which consist of coils of wire to concentrate the magnetic field.The term 'inductance' was coined by Oliver Heaviside in February 1886. It is customary to use the symbol L for inductance, possibly in honour of the physicist Heinrich Lenz.
Mutual inductance: suppose we have to coils near each other and we
pass a time-dependent current through one of them. A time dependent magnetic field results, and hence, a time
varying magnetic flux is set up in the second coil, and by Faradays law, an emf is induced in the second coil.
If the current in the first coil is I, then the induced emf in the second coil is equal to M*dI/dt, where M is a
constant known as the mutual inductance of the two coils.
Self inductance: If a time varying current is set up in a coil,
there will be a time varying magnetic field in space, and hence a time varying magnetic flux in the coil. By
Faradays law, an emf is induced in the coil (called a back emf); it is given by L*dI/dt. the constant L is
called the self inductance of the coil.
Examples that show how to calculate the mutual inductance of two
coils, as well as the self inductance of a solenoid, are presented in the lecture.
Lecture Slides are screen-captured images of important points in the lecture. Students can download and print out these lecture slide images to do practice problems as well as take notes while watching the lecture.