Ex) Suppose Q = 0.5m , N_{1} = 2000 , A_{1} = 12c * m_{j} ^ t * A_{z} = 6c * m ^ 2 N_{2} = 1000 a) Find m= (u pi+i0^ -7 Tm|4) 0.5 m (2000)(i000) (6 * 10 ^ - 4 * m ^ 2) = 3 * 10 ^ - 3 * H b) Suppose I, Changes. Steadily from OA 0.25A in 0.01 s. Find the emf in the smal coil. Em = (3x10H) C0125 A) -3 0015 = 7.5x10² V -2 Lecture # 18: (New platform, Zeem) Self-inductince • 1 coil & change incurrent enf in itsest ١٤١ 1=N1A1 = [MOA (쓴²)] [ ناه ΔΕ L = \mathcal{mu}_{0}*A((N ^ 2) / L) = Self inductance emf is in direction that oppose chages in a circuit. A transformer cosists of 7 coil-wrapped around. another. Thus same cross-sectional area. Therefore EN 2 Transformer converts voltage from wires to appropriate Voltage & tend to blowout, Quiz net week 30 mins Chept. 21 Only ElExamples: We ap Examples: We apply 120 V AC to the primary of a trousformer that has a turn ration of 2.1. What's Voltage from Seondoy?, Ez M N 200/E_{2} = 2/1 epsilon_{2} = 600 • Example of step-down transformer Ex2) Turn ratto is 116 now. 5 xi_{3} > 600V (step-up transformes). For Step-up trasformer -energ in = energy out so how 120v going bou ou ) Ej, Eiz thus = N = N2 Thus, Voltage ↑ = current & Jice versa, Energy stored in magnetic freld & energy density of magnetic field. •It solenord has a current, i, then U = 1/2 * (1) * i ^ 2 38=μο (NIL), i = B(1 / N)(1 / mu_{0}) $ Subswitute into energy Stored Lq = U = (A(1))/(2mu_{0}) * B ^ 2 Energy density, 4, U/(A(1)) = 1/(2mu_{0}) * (B ^ 2) 40 cmt boin hi F 00 00 Bremed Ause Appired fred find currant & Indeand to find force. appled freld B=2.ST Loop his mass = 60g. $ resistance =6.2. Find V. •The flux is increasing so mto Binduced points. the page, which gives a clockwoe Current, The forces on the sides concer, & the force on bottom wire is up. Loop is moung w/ constant which means F = ON. There is gravity down = my & force due to magnete field, F=ilB=100.4m)(2.5T) We know that the emf = E = SUN 3 Curent will be 틈 62 Ex/(2.5T 700.4m)v) (0.4m)(2.5T) 6 The current. F=mg = Co.05kg) 29.8 m/s²); V=2.5 m/s becaus F=0M If loop is completely in the fied the flux dosen't Change & emfo Force equals ON. thes the ve't no current & e Electromagnetic Waves

Electricity and Magnetism Lecture Note #18

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