A step-down transformer is used on a 2 2 kV lin... - JAMB Physics 2023 Question

The relationship between the number of turns on the primary (\(N_1\)) and secondary (\(N_2\)) windings of a transformer is given by the formula:

\[ \frac{{N_1}}{{N_2}} = \frac{{V_1}}{{V_2}} \]

where:
- \( N_1 \) is the number of turns on the primary winding,
- \( N_2 \) is the number of turns on the secondary winding,
- \( V_1 \) is the voltage on the primary side,
- \( V_2 \) is the voltage on the secondary side.

Given values:
\[ V_1 = 2.2 \, \text{kV} = 2200 \, \text{V} \]
\[ V_2 = 110 \, \text{V} \]
\[ N_2 = 25 \]

Now, rearrange the formula to solve for \( N_1 \):

\[ N_1 = N_2 \times \frac{{V_1}}{{V_2}} \]

Substitute the values:

\[ N_1 = 25 \times \frac{{2200}}{{110}} \]

\[ N_1 = 25 \times 20 \]

\[ N_1 = 500 \]

The number of turns on the primary winding is 500 when the secondary winding has 25 turns, and the transformer is used on a 2.2 kV line to deliver 110 V.