PHYSICS

JAMB 2022 - Question 14

Physics 2022 JAMB Past Questions - Question 14:  A transformer which can produce 10V from a 240V a.c supply has an efficiency of 60%. If the current in the secondary winding coil is 15A, the current in the primary coil is

Choose the correct answers from the options given.
 A transformer which can produce 10V from a 240V a.c supply has an efficiency of 60%. If the current in the secondary winding coil is 15A, the current in the primary coil is
A:
B:
C:
D:
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Correct Answer

B

Explanation

To find the current in the primary coil, we can use the formula:

Efficiency = (output power / input power) * 100%

Efficiency = (Pout / Pin) * 100%

Where Pout = Vout * Iout and Pin = Vin * Iin

Given that the transformer has an efficiency of 60%, the output voltage (Vout) is 10V, and the output current (Iout) is 15A. The input voltage (Vin) is 240V.

First, let's find the output power (Pout):
Pout = Vout * Iout
Pout = 10V * 15A
Pout = 150W

Now, we can use the efficiency formula to find the input power (Pin):
Efficiency = (Pout / Pin) * 100%
60% = (150W / Pin) * 100%

Solving for Pin:
Pin = 150W / (60/100)
Pin = 250W

Now, we can find the current in the primary coil (Iin):
Pin = Vin * Iin
250W = 240V * Iin

Solving for Iin:
Iin = 250W / 240V
Iin ≈ 1.04A

So, the current in the primary coil is approximately 1.04A.