To determine the number of turns on the primary winding of a step-down transformer, we need to understand how a transformer works and how the voltage is transformed from the primary to the secondary winding.
A transformer operates on the principle of electromagnetic induction. When an alternating current flows through the primary winding, it creates a changing magnetic field that induces a voltage in the secondary winding.
The voltage ratio between the primary and secondary windings is determined by the ratio of the number of turns in each winding. This means that if we decrease the number of turns in the secondary winding compared to the primary winding, we can reduce the voltage output.
In this case, we are given that the secondary winding has 25 turns and we want to deliver 110 V. The primary winding has a higher voltage, which is 2.2 kV (kilovolts) or 2200 V.
To determine the number of turns on the primary winding, we can set up a simple equation using the voltage ratios:
Primary voltage / Secondary voltage = Primary winding turns / Secondary winding turns
Plugging in the values we have:
2200 V / 110 V = Primary winding turns / 25 turns
Simplifying the equation:
20 = Primary winding turns / 25
To solve for the number of turns on the primary winding, we can cross multiply:
20 x 25 = Primary winding turns
Therefore, the number of turns on the primary winding is 500.
So, the correct answer is 500.