Physics Class 12 NCERT Solutions: Chapter 6 Electromagnetic Induction Part 4

Get top class preparation for NCO right from your home: fully solved questions with step-by-step explanation- practice your way to success.

Download PDF of This Page (Size: 261K)

Formula of Mutual Inductance

Formula of Mutual Inductance

Q: 9. A pair of adjacent coils has a mutual inductance of If the current in one coil changes from in, what is the change of flux linkage with the other coil?


Mutual inductance of a pair of coils,

Initial current,

Final current,

Time taken for the charge,

Induced emf,

Where is the change in the flux linkage with the coil.

Emf is related with mutual inductance as:

Equating equations (1) and (2), we get

Hence, the change in the flux linkage is.

Q: 10. A jet plane is travelling towards west at a speed of. What is the voltage difference developed between the ends of the wing having a span of , if the Earth’s magnetic field at the location has a magnitude of and the dip angle is .


Speed of the jet plane,

Wing span of jet plane,

Earth’s magnetic field strength,

Angle of dip,

Vertical component of Earth’s magnetic field,

Voltage difference between the ends of the wing can be calculated as:

Hence, the voltage difference developed between the ends of the wings is.

Q: 11. Suppose the loop in Exercise (Reference: Chapter 6 Electromagnetic Induction Part2) is stationary but the current feeding the electromagnet that produces the magnetic field is gradually reduced so that the field decreases from its initial value of at the rate of . If the cut is joined and the loop has a resistance of how much power is dissipated by the loop as heat? What is the source of this power?


Sides of the rectangular loop are and.

Hence, area of the rectangular wire loop,

Initial value of the magnetic field,

Rate of decrease of the magnetic field,

Emf developed in the loop is given as:


Change in flux through the loop area

Resistance of the loop,

The current induced in the loop is given as:

Power dissipated in the loop in the form of heat is given as:

The source of this heat loss is an external agent, which is responsible for changing the magnetic field with time.