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industrial uses is through a different process-conversion of mechanical energy to the electrical energy by means of suitable generators (turbines) in power houses. In this chapter we will learn about the principles involved in generation of power in this way, viz. The electromagnetic induction. 1. Electromagnetic Induction and Fardday's Experiments A scientist named Michel Faraday discovered in the year 1831 that a change in the value of the magnetic flux linked with a conducting coil give rise to the induction of an electron motive force in the coil. The emf generated this way is called the induced emf. Fig.1 illustrates simple experiment which demonstrates the electromagnetic induction. In this experiment, a sensitive galvenometer is connected in series with a conducting coil.
woons
N S In fig. I(a), a bar magnet is held stationary with respect to the coil. No deflection of galvenometer is observed under this situation. Now if the bar magnet is quickly moved towards the 1 (a) coil, with one of its poles facing the coil, the galvenometer records a deflection, showing that some current flows through the coil. It is also seen that faster the magnet is moved, greater
1 (b) is the deflection of the galvenometer, Similar effects are also observed if the coil is moved keeping the magnet fixed. Again, deflection in opposite direction is observed. When the magnet is moved away, to that recorded when
1 (c) the magnet is moved towards the coil. If the galvenometer deflects on one side when a particular pole is facing the coil (say north pole), delection of the opposite sense is recorded if the other pole is made to face the coil, when the magnet is brought near the coil. Also whenever, the coil and the magnet are stationary with respect to each
other, no deflection is observed. Teet 4511 3701 - 577, 2004
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1 (d)
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