Question

I need help with all of these questions because they are related to one question. Please show all working so I fully understand.

Answers:

2a) e = - d(N*magneticFlux) / dt

2b) I) 98 % reached in 0.144 ms

2b) ii) Max energy = 1.84 x 10^-5 J

c) i) Ns = 10 or 10.5 turns

c) ii) Rl= 500 kohm, ip= 2.08 mA

2. Write the equation for the voltage induced in a coil by a changing magnetic field. 5 Illustrate the concept on a labelled diagram and define the symbols used b) An RL circuit is shown in Figure 2b. After the switch is closed: How long does it take for the current to reach 98% of its final value? ii) Obtain the maximum energy stored in the magnetic field of the inductor. Switch 175 2 5 mH 15 V Figure 2b You are to design a transformer. i) It is required to supply a current of e) mAma at a power of 0.5 W, into a8 resistive load from a 240 V 50 Hz supply. Assume an ideal transformer and 5 turns on the primary coil. Show your design on a well labelled diagram and show all workings. ii Determine the resistance of the load used above and the current supplied to 2 the primary coil

Answer 1

This question is based on transient condition of RL circuit as soon In fig a series RL Network connected to 15 v. V with a S with which is connected at t = 0 Transient property of Inductor is that it oppose sudden change In current i_L (o^-) = L_L (o^+) at Initially t < o l_L (o^-) = 0 = L_L (o^+) so current flow throw L at t > o L_L (t) = 15/175 (1 - e^-t/tau), tau = L/R = 5 mH/175 difference In current at two condition develop rate of change of flux e = -N d emptyset/dt {Emf Induce is rate of change of flux} N is no. Of turn of Inductor (b) After the switch is closed (1) time of current to reach 98% of final value l_L (t) = 15/175 (1 - e^-t/tau) tau = L/R (time constant) \r\n V_2 = 500, V_1 = 240 working at 50 HZ V_2 > V_1 Hence Transformer is step up