Physics 2001 JAMB Past Questions - Question 43: The primary coil a transformer has N turns and is connecter to a 120 . a.c. power line. If the secondary coil has 1000 turns and a terminal voltage of 1200. what is the value of A/?

Correct Answer

B

Explanation

NP/NS=VP/VS;N/1000 =120/1200N=100 turnsIn a transformer, the ratio of the number of turns in the primary coil (N1) to the number of turns in the secondary coil (N2) is directly proportional to the ratio of the voltages. This relationship is described by the transformer equation:

V1 / V2 = N1 / N2

Where:
- V1 is the voltage across the primary coil.
- V2 is the voltage across the secondary coil.
- N1 is the number of turns in the primary coil.
- N2 is the number of turns in the secondary coil.

In your case, you have:

N1 = N (you didn't specify the number of turns, so I'm using N)
V1 = 120 V (the voltage of the AC power line)
N2 = 1000 turns
V2 = 1200 V (the terminal voltage of the secondary coil)

Now, you can plug these values into the transformer equation:

120 / 1200 = N / 1000

Now, solve for N:

N = (120 / 1200) * 1000
N = 0.1 * 1000
N = 100 turns

So, the primary coil has 100 turns. To find the value of A, you would need more information about the physical dimensions and characteristics of the transformer's core, which would determine the cross-sectional area (A) of the core. The number of turns alone does not provide enough information to calculate the value of A.