Electro Magnetic Induction And Alternating Currents Question 279
Question: A transformer with efficiency 80% works at 4 kW and 100 V. If the secondary voltage is 200 V, then the primary and secondary currents are respectively [Kerala PMT 2005]
Options:
A) 40 A, 16 A
B) 16 A, 40 A
C) 20 A, 40 A
D) 40 A, 20 A
Show Answer
Answer:
Correct Answer: A
Solution:
$ \eta =\frac{\text{output},\text{power}}{\text{input},\text{power}}=\frac{E_{s}I_{s}}{E_{p}I_{p}} $
Þ $ \frac{80}{100}=\frac{200\times I_{s}}{4\times 10^{3}} $
Þ $ I_{S}=\frac{80}{100}\times \frac{4\times 1000}{200}=16A $ Also, $ E_{p}I_{p}=4KW $
Þ $ I_{p}=\frac{4\times 10^{3}}{100}=40A $
