Test: Mutual Inductance & Coupling Coefficient - Electrical Engineering (EE) MCQ

When there is a current induced in a coil, due to the magnetic field caused by the current there is current induced in the neighbouring coil as well. This is known as mutual inductance.

A magnetic field is produced when there is a changing electric field. Hence the magnetic field is zero when the current is steady. When the magnetic field is zero there is no current induced in the other coil, thus electric field is zero.

A magnetic field is produced when there is a changing electric field. Hence the magnetic field is zero when the current is steady. When the magnetic field is zero there is no current induced in the other coil, thus electric field is zero.

Mutual inductance is the inductance between the two neighbouring coils. Since it is a type of inductance, its unit is that of inductance, that is, henry.

Mutual inductance is the product of the number of turns in one coil and the flux linkages of that coil, divided by the current in the other coil. Hence M=N2φ2/I1 is the correct expression.

We know that mutual inductance is the product of the number of turns in one coil and the flux linkages of that coil, divided by the current in the other coil.
M=3*500/2=750H.

We know that mutual inductance is the product of the number of turns in one coil and the flux linkages of that coil, divided by the current in the other coil.
N=750*2/3= 300 turns.

A magnetic field is produced when there is a changing electric field. Hence the magnetic field is zero when the current is steady.

We know that mutual inductance is the product of the number of turns in one coil and the flux linkages of that coil, divided by the current in the other coil.
φ=750*2/500= 3Wb^-t.

 We know that mutual inductance is the product of the number of turns in one coil and the flux linkages of that coil, divided by the current in the other coil.
I=3*500/750= 2A.

When all the flux of coil 1 links with coil 2 it is known as an ideal coupling where the coupling coefficient is 1.

When all the flux of coil 1 links with coil 2 it is known as an ideal coupling where the coupling coefficient is 1.

Coupling coefficient can never be equal to 1 because all the flux of coil 1 can never link with coil 2. There are bound to be losses.

Faraday’s law of induction states that, the magnitude of the induced EMF is the product of the number of turns of the coil and the rate of change of flux linkage in it. Hence, the mutual inductance depends on the rate of change of flux linkage.

The correct formula for coupling coefficient is k=M/sqrt(L1L2). Where, L1 and L2 are the inductance values of the first and second coil respectively and M is the mutual inductance.

When the flux linkage of coil 1 and coil 2 increases, its mutual inductance increases. The coupling coefficient is directly proportional to the mutual inductance hence as mutual inductance increases, the coupling coefficient increases.

The expression to find mutual inductance is k=M/sqrt(L1L2)= H/sqrt(H*H)= 1. Therefore it does not have any unit.

 we know that:
k=M/sqrt(L1L2)
Substituting the values from the question, we get k=5.

we know that:
k=M/sqrt(L1L2)
Substituting the values from the question, we get M=20H.

we know that:
k=M/sqrt(L1L2)
Substituting the values from the question, we get L1=2H.