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Electromagnetic Induction Current Induced in a Straight Conductor Current Induced in a Loop of Wire Faraday’s Law of Induction Magnetic Flux Lenz’s Law Homework Current Induced in a Straight Conductor A conductor of length moves with velocity through a uniform magnetic field perpendicular to . A current is induced in the conductor due to the magnetic force on charges in the conductor. Serway/Jewett Figure 23.1 Current Induced in a Loop of Wire A current is induced in the loop when a magnet is moved toward the loop. No current is induced in the loop when the magnet is stationary. When the magnet is moved away from the loop. A current is induced in the opposite direction. Serway/Jewett Figure 23.2 Faraday’s Law of Induction The induced emf in a circuit is equal (except for a negative sign) to the rate at which the magnetic flux through the circuit changes with time. The SI unit of magnetic flux is the weber (Wb): 1 Wb = 1 T.m The negative sign is an indication of the direction of the induced emf. When applying Faraday’s law to a coil with turns, an emf appears in every turn and these emfs add. Magnetic Flux The magnetic flux through ele a differential ment of area is given by = . Note that the vector face. is perpendicular to the sur- Serway/Jewett Figure 23.4 Example A 1000-turn coil is 10.0 cm in diameter. What emf is developed across the coil if the magnetic field through the coil is reduced from 6.00 T to 0.00 in (a) 1.00 s, (b) 0.100 s, and (c) 0.100 ms? dA Bi "! % /! G # 0214365587 ! , G 02IJ9K G [email protected]: [email protected]: F 9 D D :<5 E 0L:<555M9 N :<5E :<5E ?SAC:VU . D ?SAC3T:VU 0XWY9 F :<5 :3655RQ , F F [email protected]: 0 D , () * [email protected]: 5 G +-, ( . '( &% , * +-, () H $ '( 543;:<55>= ( 9 ?SAC:VZ[U E FPO Lenz’s Law The induced current will appear in such a direction that it opposes the change that produced it. That is, the induced current is in a direction such that the induced magnetic field attempts to maintain the original flux through the loop. Serway/Jewett Figure 23.16 Homework Set 23 - Due Fri. May 28 Read Sections 23.1 & 23.3 Answer Question 23.1 Do Problems 23.1, 23.3 & 23.6