20.5b Ex2 MJ08 P4 Q6 Motor vs Dynamo | A2 Magnetic Induction | CAIE A Level 9702 Physics

Example 2 - 9702/4/M/J/08: A small rectangular coil ABCD contains 140 turns of wire. The sides AB and BC of the coil are of lengths 4.5 cm and 2.8 cm respectively, as shown in Fig. 6.1. The coil is held between the poles of a large magnet so that the coil can rotate about an axis through its centre. The magnet produces a uniform magnetic field of flux density B between its poles. When the current in the coil is 170 mA, the maximum torque produced in the coil is 2.1 × 10–3 N m. #9702s08p4 #Lv3 #A2forceOnConductorP4 #A2movingConductorsP4 (a) For the coil in the position for maximum torque, state whether the plane of the coil is parallel to, or normal to, the direction of the magnetic field. (b) For the coil in the position shown in Fig. 6.1, calculate the magnitude of the force on(i) side AB of the coil, (ii) side BC of the coil. (c) Use your answer to (b)(i) to show that the magnetic flux density B between the poles of the magnet is 70 mT. (d) (i) State Faraday’s law of electromagnetic induction. (ii) The current in the coil in (a) is switched off and the coil is positioned as shown in Fig. 6.1. The coil is then turned through an angle of 90° in a time of 0.14 s. Calculate the average e.m.f. induced in the coil. Simulations: 3D Rotating Coil in Field (https://www.geogebra.org/m/dgedzmz3#material/QJdqdmbR) DC Motor (https://www.geogebra.org/m/PN2YrxBb) #A2magneticInduction Playlist: /playlist/PLXli3LrRvG-ZQRFyqXRHK6xAokj45I_6q Instagram Pocket Guide (https://www.instagram.com/etphysics/) More Resources (https://9702-physics.blogspot.com/) Support us! (https://patreon.com/etphysics) Tuition/Tutoring inquiries: Email: suitlin@gmail.com Whatsapp: https://wa.me/60126679171 9702_s08_qp4 #CambridgeALevelPhysics

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