Step-down transformer

Definition

A step-down transformer is a device that decreases the voltage from the primary coil to the secondary coil while increasing the current. It is commonly used to convert high voltage electricity from power lines to a lower, safer voltage for use in homes and businesses.

5 Must Know Facts For Your Next Test

1. A step-down transformer has more turns of wire on its primary coil than on its secondary coil.
2. The voltage ratio between primary and secondary coils is equal to the turns ratio of those coils.
3. Energy transfer in an ideal transformer is nearly 100% efficient, meaning power input equals power output ($P_{in} = P_{out}$).
4. Step-down transformers are crucial for reducing transmission losses by allowing electricity to be transmitted at high voltages and then reduced near usage points.
5. The equation $V_p / V_s = N_p / N_s$ relates primary voltage ($V_p$) and secondary voltage ($V_s$) to the number of turns in the primary ($N_p$) and secondary ($N_s$) coils.

Review Questions

• What is the role of a step-down transformer in an electrical circuit?
• How does the turns ratio affect the voltage transformation in a step-down transformer?
• Why are step-down transformers important for electrical transmission systems?

Related terms

Primary Coil:

The coil of a transformer that is connected to the input voltage source.

Secondary Coil:

The coil of a transformer where the transformed (reduced or increased) output voltage is obtained.

Turns Ratio: The ratio of the number of turns in the primary coil to the number of turns in the secondary coil, determining the change in voltage.