Electromagnetic Induction and Alternating Current 7 Question 2

2. A power transmission line feeds input power at 2300V to a step-down transformer with its primary windings having 4000 turns. The output power is delivered at 230V by the transformer. If the current in the primary of the transformer is 5A and its efficiency is 90, the output current would be

(Main 2019, 9 Jan II)

(a) 45A

(b) 50A

(c) 25A

(d) 35A

Show Answer

Answer:

Correct Answer: 2. (a)

Solution:

  1. For a transformer, there are two circuits which have Np and Ns (number of coil turns), Ip and IS (currents) respectively as shown below.

Here, input voltage, Vp=2300V

Number of turns in primary coil, NP=4000

Output voltage, VS=230 volt

Output power, PS=VSIS

Input power, PP=VPIP The efficiency of the transformer is

η= Output (secondary) power  Input (primary) power η=VSISVPIP×100η=(230)(IS)(2300)(5)×10090=230IS(2300)×5×100IS=45A



जेईई के लिए मॉक टेस्ट

एनसीईआरटी अध्याय वीडियो समाधान

दोहरा फलक