A step-up transformer does what?

A step-up transformer does what?

• A. Decreases voltage from primary to secondary
• B. Increases voltage from primary to secondary
• C. Keeps voltage the same from primary to secondary
• D. Converts AC to DC

Answer: (B)

A step-up transformer increases voltage from the primary to the secondary. In an ideal transformer, the voltages relate to the turns on each winding: Vs = Vp × (Ns/Np). Since Ns (the secondary turns) is greater than Np in a step-up, the secondary voltage becomes higher than the primary. Power stays roughly the same (minus losses), so the secondary current is lower: Is ≈ Ip × (Np/Ns). This is why it’s used to push electrical power at higher voltage with lower current over long distances. The other options don’t fit: decreasing voltage would be a step-down transformer; keeping the voltage the same describes a 1:1 transformer; and converting AC to DC is done by a rectifier, not a transformer.

A step-up transformer increases voltage from the primary to the secondary. In an ideal transformer, the voltages relate to the turns on each winding: Vs = Vp × (Ns/Np). Since Ns (the secondary turns) is greater than Np in a step-up, the secondary voltage becomes higher than the primary. Power stays roughly the same (minus losses), so the secondary current is lower: Is ≈ Ip × (Np/Ns). This is why it’s used to push electrical power at higher voltage with lower current over long distances. The other options don’t fit: decreasing voltage would be a step-down transformer; keeping the voltage the same describes a 1:1 transformer; and converting AC to DC is done by a rectifier, not a transformer.