State Lenz's Law and how it relates to energy conservation.

Lenz's Law: The induced current always flows in a direction that opposes the change causing it. If a magnet approaches a coil, the induced current creates a magnetic pole to repel the magnet — you must do work to push the magnet in. This mechanical work is converted to electrical energy. If the induced current aided the magnet's motion, it would perpetually accelerate — violating conservation of energy.

What is the difference between self-inductance and mutual inductance?

Self-inductance (L): The property of a coil to oppose changes in its own current by inducing an EMF in itself. ε = −L(dI/dt). Mutual inductance (M): The property of two coils whereby changing current in one induces EMF in the other. ε₂ = −M(dI₁/dt). Transformers work on mutual inductance principle.

What are eddy currents and how can they be reduced?

Eddy currents are loops of current induced in bulk conductors (like transformer iron cores) when the magnetic flux through them changes. They cause energy loss as heat. Reduced by: using laminated cores (thin sheets of iron insulated from each other) — this increases resistance to eddy current flow, greatly reducing their magnitude and energy loss.

Faraday's Laws of Electromagnetic Induction

Electromagnetic Induction • Class 12 Physics • NCERT • CBSE

Faraday's First Law: EMF is induced whenever magnetic flux through a coil changes. Faraday's Second Law: Induced EMF = −dΦ/dt (rate of change of flux). Lenz's Law: Induced current opposes the change causing it. Self-inductance L: EMF = −L(dI/dt). Mutual inductance M: E₂ = −M(dI₁/dt).

Key Formulas

ε = −dΦ/dt (Faraday's 2nd Law)
ε = −N(dΦ/dt) (N-turn coil)
Motional EMF: ε = Blv
ε = −L(dI/dt) (self-induction)
U = ½LI² (inductor energy)
ε₀ = NBAω (peak EMF of AC generator)

Frequently Asked Questions

State Lenz's Law and how it relates to energy conservation.: Lenz's Law: The induced current always flows in a direction that opposes the change causing it. If a magnet approaches a coil, the induced current creates a magnetic pole to repel the magnet — you must do work to push the magnet in. This mechanical work is converted to electrical energy. If the induced current aided the magnet's motion, it would perpetually accelerate — violating conservation of energy.
What is the difference between self-inductance and mutual inductance?: Self-inductance (L): The property of a coil to oppose changes in its own current by inducing an EMF in itself. ε = −L(dI/dt). Mutual inductance (M): The property of two coils whereby changing current in one induces EMF in the other. ε₂ = −M(dI₁/dt). Transformers work on mutual inductance principle.
What are eddy currents and how can they be reduced?: Eddy currents are loops of current induced in bulk conductors (like transformer iron cores) when the magnetic flux through them changes. They cause energy loss as heat. Reduced by: using laminated cores (thin sheets of iron insulated from each other) — this increases resistance to eddy current flow, greatly reducing their magnitude and energy loss.

Study With GyanAI

GyanAI's AI tutor can answer any question about this topic instantly. Try GyanAI free for step-by-step NCERT solutions aligned with the CBSE curriculum.