Question

an induced emf of 2 v is set up in a coil when current changes at the rate of 4A/s . the self inductance of the coil is​

Answer 1

Answer:

coil has an inductance, ( L ) of one Henry, ( 1H ) when the current flowing through the coil changes at a rate of one ampere/second, ( A/s ). This change induces a voltage of one volt, ( VL ) in it. Thus the mathematical representation of the rate of change of current through a wound coil per unit time is given as:

current through a coil

Where: di is the change in the current in Amperes and dt is the time taken for this current to change in seconds. Then the voltage induced in a coil, ( VL ) with an inductance of L Henries as a result of this change in current is expressed as:

voltage induced in a coil

Note that the negative sign indicates that voltage induced opposes the change in current through the coil per unit time ( di/dt ).

From the above equation, the inductance of a coil can therefore be presented as:

Inductance of a Coil

inductance equation

Where: L is the inductance in Henries, VL is the voltage across the coil and di/dt is the rate of change of current in Amperes per second, A/s.

Inductance, L is actually a measure of an inductors “resistance” to the change of the current flowing through the circuit and the larger is its value in Henries, the lower will be the rate of current change.

We know from the previous tutorial about the Inductor, that inductors are devices that can store their energy in the form of a magnetic field. Inductors are made from individual loops of wire combined to produce a coil and if the number of loops within the coil are increased, then for the same amount of current flowing through the coil, the magnetic flux will also increase.

So by increasing the number of loops or turns within a coil, increases the coils inductance. Then the relationship between self-inductance, ( L ) and the number of turns, ( N ) and for a simple single layered coil can be given as: