LED (Light Emitting Diode) emits light when forward biased, due to recombination of electrons and holes. Efficient, long life. Used in displays, lighting. Laser is Light Amplification by Stimulated Emission of Radiation.
Explanation:
Electric generators convert mechanical energy to electrical energy using electromagnetic induction: rotating a coil in magnetic field (or vice versa) induces EMF due to changing magnetic flux. This is Faraday's law application. Motors use the reverse principle (force on current-carrying conductor in field). Memory tip: 'Generator: motion ⇒ electricity (induction); Motor: electricity ⇒ motion (force)'. This application question tests understanding of device principles, common in competitive exams. Always distinguish generator (induction) from motor (Lorentz force) operation.
Explanation:
Pole strength is a property of the magnet; when cut transversely, each piece still has both north and south poles with same pole strength as original. Magnetic moment becomes half because length halves. Each is a complete magnet.
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