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#coil polarity

2 public questions tagged with this topic.

Magnetic Flux and Faraday's Laws of Induction

A magnet is moved away from a coil, and the induced current flows clockwise as viewed from the magnet. What is the polar

**Faraday's first law** emf induced when flux linking coil changes, second law magnitude proportional to rate of change, e = -dΦ/dt, for N turns e = -N dΦ/dt, flux Φ = B A cosθ, change can be due to B change, A change, or θ change, all produce emf. By Lenz’s law, the clockwise current opposes the decreasing flux by producing a south pole facing the receding north pole of the magnet, creating an attractive force. Using Φ = B A cosθ, e = -N dΦ/dt = -N A dB/dt = B l v = N B A ω sinωt, L = μ₀ N²A/l, M

Ref: NCERT > Physics Book > Electromagnetic Induction > Magnetic Flux and Faraday's Laws of Induction

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Lenz's Law, Eddy Currents and Applications

A magnet is moved towards a coil with its south pole first. The coil’s face nearest the magnet becomes what pole to oppo

**Solenoid second coil** experiences emf only when current in solenoid changes because flux linkage changes only then, steady current gives constant Φ, dΦ/dt=0, no emf, when current changes, dΦ/dt ≠0, emf induced, illustrating Faraday's law requirement of changing flux. Lenz’s law dictates that the induced current creates a south pole to repel the approaching south pole, opposing the flux increase. Using Φ = B A cosθ, e = -N dΦ/dt = -N A dB/dt = B l v = N B A ω sinωt, L = μ₀ N²A/l, M = e/(dI/dt) and U = ½ L I², result South follows, reflecting Faraday's law and Lenz's opposition.

Ref: NCERT > Physics Book > Electromagnetic Induction > Lenz's Law, Eddy Currents and Applications

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