Question

An ideal transformer has 500 and 5000 turns in primary and secondary winding respectively. If the primary coil is connected to a 6 V battery then the secondary voltage is :

• A. 60 V
• B. Zero
• C. 0.6 V
• D. 6.0 V

Answer 1

Answer: (A)

Answer is A.

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.
The Turns Rule is:
Ns/Np=Vs/Vp
Where,
Ns = number of turns on the secondary coil
Np = number of turns on the primary coil
Vs = voltage across the secondary coil
Vp = voltage across the primary coil
So if number of turns on the secondary coil is more than on the primary coil, the output voltage will be higher than the input voltage. This is called a step up transformer.
Hence, The secondary voltage as per the given question can be obtained as follows:
Let input voltage be 6V and the output voltage be x. Let 5000 be the number of turns of secondary coil and 500 be the number of turns of primary coil.
Ns/Np=Vs/Vp;
That is, 5000/500=x/6
$x=\frac{5000\times 6}{500}=60V$.
Therefore, the secondary voltage is 60 V.