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 ΦB = 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 = -M12\(\frac{\mathrm{dI}}{\mathrm{dt}}\)
→ Energy stored in a magnetic field (u) = \(\frac{1}{2} \mathrm{LI}_0^2\)
→ Self inductance of a solenoid L = μ0n2Al.
→ Mutual inductance of two long solenoids M = μ0n1n2Al
→ 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