How does a transformer alter voltage and current?

How does a transformer alter voltage and current?

• A. It stores energy like a battery.
• B. It changes voltage according to turns ratio; current changes inversely to voltage, power remains approximately constant.
• C. It converts AC to DC.
• D. It increases both voltage and current proportionally.

Answer: (B)

The key idea is that a transformer changes voltage through its turns ratio and adjusts current so that power stays roughly the same. The voltage on the secondary is set by how many turns are on the primary compared to the secondary: more turns on the primary than on the secondary give a lower secondary voltage, and fewer turns on the primary give a higher secondary voltage. Because power is approximately conserved in an ideal transformer, the current on the secondary adjusts inversely with the voltage: if the secondary voltage goes down, the secondary current goes up, and if the secondary voltage goes up, the secondary current goes down. This keeps the product of voltage and current, the power, nearly constant. An easy way to picture it is to think about energy flowing from the input to the output through the magnetic field. The transformer isn’t storing energy like a battery; it’s transferring energy and reshaping it. Why the other ideas don’t fit: a transformer doesn’t convert AC to DC—that’s what a rectifier does. It also doesn’t increase both voltage and current at the same time; doing so would require more power input than available, which contradicts the idea of energy balance in an ideal transformer.

The key idea is that a transformer changes voltage through its turns ratio and adjusts current so that power stays roughly the same. The voltage on the secondary is set by how many turns are on the primary compared to the secondary: more turns on the primary than on the secondary give a lower secondary voltage, and fewer turns on the primary give a higher secondary voltage. Because power is approximately conserved in an ideal transformer, the current on the secondary adjusts inversely with the voltage: if the secondary voltage goes down, the secondary current goes up, and if the secondary voltage goes up, the secondary current goes down. This keeps the product of voltage and current, the power, nearly constant.

An easy way to picture it is to think about energy flowing from the input to the output through the magnetic field. The transformer isn’t storing energy like a battery; it’s transferring energy and reshaping it.

Why the other ideas don’t fit: a transformer doesn’t convert AC to DC—that’s what a rectifier does. It also doesn’t increase both voltage and current at the same time; doing so would require more power input than available, which contradicts the idea of energy balance in an ideal transformer.