Electromagnetic Induction Class 12 Notes Physics Chapter 6 - CBSE
Chapter : 6
What are Electromagnetic Induction ?
https://drive.google.com/file/d/1w-kBiOIYGF668Qxjovt19_5odboQCYKz/view
Electromagnetic Induction
- The phenomenox of production of emf in a coil, when magnetic flux linked with the coil is changed.
where B is the strength of magnetic field, A is the area of surface and θ is the angle which normal to the area makes with the direction of magnetic field.
- The SI unit of magnetic flux is weber (Wb).
Faraday’s Laws
- First Law : Whenever there is a change in magnetic flux linked with a circuit, an emf is induced in the circuit, till change in flux keeps on changing.
- Second Law : The induced emf is directly proportional to the time rate of change of magnetic flux.
- Faraday’s laws are the consequence of the conservation of energy.
Induced Emf And Current
- Faraday’s second law of electromagnetic induction gives the magnitude of induced emf/current.
Induced emf, ε =(-dΦ/dt),
where negative sign indicates the direction of ε.
- Induced current, i =(induced emf/resistance)=|ε|/R=(dΦ/dt/(R))
- Induced emf is measured in volt (V).
Lenz’s Law
- This law gives the direction of induced emf. According to Lenz’s law, the polarity of the induced emf is such that it tends to produce a current which opposes the change in magnetic flux that produces it.
- Lenz’s law is in accordance with the principle of conservation of energy.
Self Induction
- When a current in a coil changes, it induces a back emf in the same coil, this phenomenon is known as self inductance. Self induced emf is given by, ε =(-LdI/dt), where L is the coefficient of self inductance of the coil.
- SI unit of self inductance is henry (H)
Mutual Induction
- When an emf is produced in a coil because of change in current in a coupled coil, this effect is called mutual inductance.
- If Φ is the amount of magnetic flux linked with one coil (primary) when a current I flows through the other (secondary) coil, then Φ = MI, where M is coefficient of mutual inductance of the two coils. Emf induced in the secondary coil is, ε = –M(dI/dt)
- SI unit of mutual inductance is henry (H)
