Question

a) In a television set the power needed to operate the picture tube comes from the secondary of a transformer. The primary of the transformer is connected to a 120-V receptacle on a wall. The picture tube of the television set uses 86 W, and there is 5.5 mA of current in the secondary coil of the transformer to which the tube is connected. Find the turns ratio N_s/N_p of the transformer.

b) A constant current of I = 15 A exists in a solenoid whose inductance is L = 3.9 H. The current is then reduced to zero in a certain amount of time. (a) If the current goes from 15 to 0 A in a time of 75 ms, what is the emf induced in the solenoid? (b) How much electrical energy is stored in the solenoid? (c) At what rate must the electrical energy be removed from the solenoid when the current is reduced to 0 A in a time of 75 ms? Note that the rate at which energy is removed is the power.

thank you!

Answer 1

Solution as from the Relatten blue a/allage hato and Numbel of them in tlaufarmes in Vs Ne Ps Is 8 que 5.5 8103A 120 NS 130.30 NP 5 L=.3.9H en Lide at - 3.9 X 15 75 X 10-3 e = Isov E - 1 x LX iz 1 X 3.94152 438.75J U P= E t 438.75 75 X 10^3 P=5850 w