Physics · Alternating Current

When Ns > Np, the transformer is a step-up transformer.

Here, Ns represents the number of turns in the secondary coil and Np represents the number of turns in the primary coil. In a step-up transformer, the number of turns in the secondary coil is greater than the number of turns in the primary coil.

In a step-up transformer, the input voltage is applied across the primary coil, and the output voltage is obtained across the secondary coil. Since the number of turns in the secondary coil is greater than the number of turns in the primary coil, the voltage across the secondary coil is greater than the voltage across the primary coil. This results in a step-up in voltage from the primary to the secondary coil, hence the name "step-up" transformer. 

This option is correct. Step-up: In a step-up transformer, the number of turns in the secondary coil (Ns) is greater than the number of turns in the primary coil (Np). This increases the voltage from the primary to the secondary side.

This is the incorrect option.Step-down: In a step-down transformer, Ns is less than Np, decreasing the voltage.

* Primary/Secondary: These refer to the input and output sides of the transformer, not the relationship between the number of turns.

* Primary/Secondary: These refer to the input and output sides of the transformer, not the relationship between the number of turns.