Students can go through AP Inter 2nd Year Physics Notes 9th Lesson Electromagnetic Induction will help students in revising the entire concepts quickly.

## AP Inter 2nd Year Physics Notes 9th Lesson Electromagnetic Induction

→ Changing magnetic field can produce electric current.

→ Magnetic flux is the number of magnetic lines linked with a conductor.

→ Faraday’s experiments led to the discovery to the phenomenon of electromagnetic induction.

→ The changing magnetic flux linked with a coil, induces emf is the coil.

→ Induced e.m.f is proportional to the rate of change of the magnetic flux.

→ Lenz’s law states that the direction of induced e.m.f is such that it always opposes the cause which produces it.

→ Eddy currents (or) Focault’s currents are the currents induced in a conductor, when placed in a changing magnetic field.

→ Eddy currents have both practical useful applications as well as undesirable effects.

→ Non-inductance coils are used in the resistance boxes to avoid the effects of self-induction.

→ A wire cannot act as an inductor because the magnetic flux linked with the wire of negligible area of cross-section is zero.

→ A wire in the form of a coil can serve as an inductor.

→ A long solenoid is that whose length is very large as compared to its radius of crosssection.

→ Laws of electromagnetic induction are

- When ever the magnetic flux linked with a circuit changes, an induced e.m.f is produced in the circuit.
- The magnitude of e.m.f induced in a circuit is directly proportioned to the rate of change of magnetic flux linked with the circuit.

→ When a current in the coil changes, magnetic flux changes, hence on induced e.m.f is set up in it. This phenomenon is called self induction.

→ When a current is one coil changes, magnetic flux changes in it, hence an e.m.f is induced in the another coil near by it. This phenomenon is called mutual-induction.

Formulae

→ Magnetic flux Φ_{B} = B . A = BA cos θ.

→ ε = \(\frac{-\mathrm{d} \phi_{\mathrm{B}}}{\mathrm{dt}}\)

→ ε = -N \(\frac{\mathrm{d} \phi}{\mathrm{dt}}\)

→ Motional e.m.f ε = Blυ

→ ε = -L \(\frac{\mathrm{dI}}{\mathrm{dt}}\)

→ ε = -M_{12}\(\frac{\mathrm{dI}}{\mathrm{dt}}\)

→ Energy stored in a magnetic field (u) = \(\frac{1}{2} \mathrm{LI}_0^2\)

→ Self inductance of a solenoid L = μ_{0}n^{2}Al.

→ Mutual inductance of two long solenoids M = μ_{0}n_{1}n_{2}Al

→ Instanteneous induced e.m.f. (ε) = NBAω sin ωt.

→ F = \(\mathrm{q}(\overrightarrow{\mathrm{E}}+\vec{v} \times \overrightarrow{\mathrm{B}})\)

→ Power (p) = \(\frac{\mathrm{B}^2 l^2 v^2}{\mathrm{r}}\)

→ NΦ = LI

→ NΦ = MI