A transformer has 90 turns in the primary coil and 9 turns in the secondary coil If the output voltage is 6 V, what is the input voltage

Given:

As we know,

→

or,

→

By substituting the values, we get

Thus the above answer is  correct.

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60 V

Explanation:

From;

Vs/Vp = Ns/Np

Where;

Vs = voltage in the secondary coil = 6V

Vp = voltage in the primary coil= ??

Ns = number of turns in the secondary coil = 9

Np= number of turns in the primary coil = 90

6/Vp = 9/90

Vp= 90 * 6/9

Vp=  60 V

the answer is d. 74.02