Answer:
There are two correct options.
1. A transformer is used to increase or decrease an alternating current voltage.
2. In a transformer, if the secondary coil contains more loops than the primary coil, then it is a step-up transformer.
Explanation:
A transformer is a device which has two coils. One is primary coil and other is secondary coil.
Input is given to primary coil and output is taken out from secondary coil.
A transformer can increase or decrease the output voltage by setting the number of turns in primary and secondary coil.
If the number of turns in primary coil is less than the number of turns in secondary coil, then it is step up transformer. It increases the output voltage.
The relation between the number of turns and the voltage is given by
Where, Np = number of turns in primary coil
Ns = number of turns in secondary coil
Vp = ac voltage across primary coil
Vs = ac voltage across secondary coil
Ip = ac current across primary coil
Is = ac current across secondary coil