Question

A step-up transformer of turns ratio $2:1$ has $50Hz$ $AC$ voltage applied to primary. The frequency of $AC$ output voltage across secondary is

• A. Zero
• B. $25Hz$
• C. $50Hz$
• D. $100Hz$

Answer 1

The correct option is C $50Hz$

Answer is C.

A transformer takes high-voltage electricity with a small current and changes it into low-voltage electricity with a large current, or vice versa. That is, step up or step down the voltage in a circuit. A step-up transformer turns low-voltage electricity into high-voltage electricity while dropping the current. A step-down transformer changes high-voltage electricity into low-voltage electricity.
If we change the number of turns in the coils we change the induced emf. This allows us to change (transform) the voltage from the primary to the secondary coil.
Here, the turns ratio is 2:1 and so the voltage ratio will also be 2:1.
In this case, the frequency of the input AC voltage is 50 Hz. The output voltage will also have a frequency of 50 Hz as the frequency does not change when the voltage increases.
Voltage is potential difference between two points in a electrical circuit. Frequency means number of cycles of sinusoildal wave per second.
Hence, the frequency of the output voltage is also 50 Hz.