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Electromagnetic Induction. Group: Induction Wong Chun Jie Leong Qi Dong Jwa Li Wen 4S2 2012 T3. Introduction. Current flowing through a conductor produces a magnetic field Can a magnetic field produce a current in a conductor?. Video. http://www.youtube.com/watch?v=ITuR3AQAYI8
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Electromagnetic Induction Group: Induction Wong Chun Jie Leong Qi Dong Jwa Li Wen 4S2 2012 T3
Introduction • Current flowing through a conductor produces a magnetic field • Can a magnetic field produce a current in a conductor?
Video • http://www.youtube.com/watch?v=ITuR3AQAYI8 • 1:07:50 – 1:10:4`
Theory – Electromotive Force (emf) A varying magnetic flux produced an e.m.f, which produces an induced current in a closed circuit.
Steps 1. Move magnet into solenoid 2. Leave the magnet in solenoid 3. Move magnet out of solenoid
Variables Dependent: (1) Deflection of galvanometer pointer (2) Direction of deflection (3) Magnitude of deflection Independent: • Pole of magnet • Number of turns in solenoid • Strength of magnet • Cross-sectional area of solenoid • Speed of magnet being moved in and out
Results (1) Deflection of galvanometer pointer • Deflects: magnet is moving in and out of solenoid • Does not deflect: magnet remains stationary in solenoid • Current is flowing through circuit only when the magnet is moving in and out of the solenoid
Conclusion • A varying magnetic field produces an e.m.f, which produces an induced current in a closed circuit.
Results (2) Direction of deflection
Conclusion Lenz’s Law • The direction of the induced emf, and thus, the induced current in a closed circuit, is always such that the magnetic effect always opposes the change producing it. • Why oppose? • In Work, Energy, Power: GPE = KE • In Electromagnetic Induction: GPE = KE + Electrical energy • KE decreases for the conservation of energy
Results (3) Magnitude of deflection Increase in • number of turns in solenoid • strength of magnet • cross-sectional area of solenoid • speed of magnet being moved in and out Increases deflection – increases emf N ΦB Rate
Conclusion • Faraday’s Law of Induction • Where ℰ is the emf • Induced emf generated in a conductor is proportional to the rate of change of magnetic flux vectorlinking the circuit.
References • http://physics.tutorvista.com/electricity-and-magnetism.html#close_iframe • http://en.wikipedia.org/wiki/Faraday's_law_of_induction • http://en.wikipedia.org/wiki/Magnetic_flux • http://en.wikipedia.org/wiki/Electromotive_force