gen-briefly-explain-the-transformer-turns-ratio-and-one-common-m-464e

Briefly explain the transformer turns ratio and one common misconception about it.

# Transformer Turns Ratio **Definition:** The turns ratio is the ratio of the number of wire windings on the primary coil to the secondary coil (Np:Ns). This ratio directly determines the voltage transformation: **Vp/Vs = Np/Ns** For example, a 10:1 turns ratio steps down voltage by a factor of 10. ## Common Misconception **Misconception:** "A step-down transformer reduces power consumption." **Reality:** An ideal transformer doesn't reduce power—it transforms voltage and current while keeping power constant (P = V × I). When voltage is stepped down, current is stepped *up* proportionally, so: **Vp × Ip = Vs × Is** A 10:1 step-down transformer that reduces voltage from 120V to 12V will increase current by roughly 10 times. The power remains the same (minus small losses). This is why the secondary winding of a step-down transformer typically uses thicker wire—to handle the higher current.