### Electromagnetic Induction Electromagnetic Induction

**Electromagnetic Concepts for JEE Main & Advanced**

**Faraday’s law of electromagnetic induction:**

- Explains the generation of electromotive force (EMF) in a conductor when the magnetic flux linked with it changes.
**Key Points:****EMF(ε) = -dΦ/dt**- Negative sign indicates opposing nature.

**Lenz’s Law:**

- Describes the direction of induced EMF and current flow according to the conservation of energy.
**Key points:**- Opposes the change in magnetic flux.
- Induced current produces a magnetic field that counteracts the change.

**Magnetic Flux(Φ)**

- Represents the amount of magnetic field passing through a given area.
**Key Points:**- Defined as the dot product of magnetic field strength (B) and area vector (A)
- Φ = B⋅Acosθ.

**Electromotive Force (EMF):**

- Work done in moving a unit charge around a closed loop due to electromagnetic induction.
**Key Points:**- Unit:
**Volt (V)** - Can be expressed as the rate of change of magnetic flux.

- Unit:

**Induced Current:**

- The flow of electric charges in a conductor due to electromagnetic induction.
**Key Points:**- Magnitude determined by the rate of change of magnetic flux.
- Direction given by Lenz’s law.

**Self-inductance (L):**

- Property of a conductor that opposes changes in its own current flow.
**Key Points:**- Coefficient that relates the change in magnetic flux to the rate of change of current.
- Expressed as L = Φ/I

**Mutual Inductance (M):**

- Interaction between two different conductors where the change in current of one induces an EMF in the other.
**Key points:**- Coefficient relating induced EMF in one coil to the rate of change of current in the other.
- M = Φ/I

**Energy Stored in a Magnetic Field:**

- Represents the energy contained within a magnetic field.
**Key Points:**- U = (1/2)LI^2
- Proportional to the square of current flowing through the inductor.

**AC Generators:**

- Devices that convert mechanical energy into alternating current (AC) electricity.
**Key Points:**- Utilize electromagnetic induction.
- Rotating coils induce EMF in stationary conductors.

**AC Motors:**

- Machines that convert electrical energy into mechanical energy using alternating current (AC).
**Key Points:**- Work on the principle of electromagnetic induction in reverse.
- Rotating magnetic field created by multiple alternating currents.

**Transformers:**

- Devices that transfer electrical energy from one circuit to another by electromagnetic induction.
**Key Points:**- Consist of primary and secondary coils with different numbers of turns.
- EMF induced in the secondary coil according to Faraday’s law.

**Key Concepts for CBSE Boards:**

**Faraday’s Law of Electromagnetic Induction:**

- Explains how changing magnetic fields induce electromotive force (EMF) and electric currents.

**Lenz’s Law:**

- Describes the direction of induced EMF and current according to the conservation of energy.

**AC Generators:**

- Convert mechanical energy into alternating current (AC) electricity using electromagnetic induction.

**AC Motors:**

- Convert electrical energy into mechanical energy using alternating current (AC) and electromagnetic induction.

**Basic Idea of Self-Inductance and Mutual Inductance:**

- Self-inductance opposes changes in current flow in a single conductor, while mutual inductance involves the interaction between two conductors where the change in current of one induces an EMF in the other.