Question

The primary coil of a transformer has \[800\] turns and the secondary coil has $8$ turns. It is connected to a \[220V\] A.C. supply. What will be the output voltage?
A. $2V$
B. $2.2V$
C. $220V$
D. $22V$

Answer 1

Hint: In this question, we need to determine the output voltage of the transformer such that the number of the turns of the conductor in the primary and the secondary coils are 800 and 8 respectively and is being applied to 220 volts of AC power supply. For this, relation between the output and the input power has been established and output voltage is obtained by the product of input voltage and the efficiency of a transformer.

Complete step by step answer:
The efficiency of a transformer can be calculated as the ratio of the number of turns in the secondary coil to the number of turns in the primary coil.
Again the efficiency can also be defined as the ratio of output voltage to the input voltage.
We use the above relation and thus the output voltage will be
$\dfrac{{{N_S}}}{{{N_P}}} = \dfrac{{{V_{OUT}}}}{{{V_{IN}}}}$
${V_{OUT}} = \dfrac{{{N_S}}}{{{N_P}}}{V_{IN}} = \dfrac{8}{{800}}220 = 2.2V$

So, the correct answer is “Option B”.

Note:
It is important to note here that it is due to mutual inductance that the voltage is generated in the secondary coil. The magnitude of voltage depends on the number of turns in the primary and secondary coil. In a transformer always the power remains constant. The ratio should be used correctly.