Question

The transformation ratio of a transformer is 10:1. If the primary voltage is 440 Then find out the secondary emf is?
A- 44 V
B- 440 V
C- 4400 V
D- 44000 V

Answer 1

Hint: In a transformer there are two coils one is called primary coil and the other is called the secondary coil. Depending upon whether the transformer is step up or step down, the number of turns in one coil is greater than the other. The transformer works on the principle of magnetic induction. Transformation ratio has a unique relationship between the number of turns in the two coils.

Complete step by step answer:
Transformation ratio is defined as the ratio of number of turns in primary to number of turns in secondary. Writing it mathematically \[N=\dfrac{p}{s}\], where N is the transformation ratio which is given here as 10:1 and p is the number of turns in the primary coil and s is the number of turns in the secondary coil.
\[\Rightarrow 10=\dfrac{p}{s}\]
Since, voltage is directly proportional to number of turns,
\[\Rightarrow \dfrac{{{V}_{p}}}{{{V}_{s}}}=10=\dfrac{p}{s}\]
Given primary voltage is 440 V, thus,
\[\Rightarrow \dfrac{440}{{{V}_{s}}}=10\]
\[\therefore {{V}_{s}}=44V\]

Additional Information:
When a transformer is used to “increase” the voltage on its secondary winding with respect to the primary, it is called a Step-up transformer. When it is used to “decrease” the voltage on the secondary winding with respect to the primary it is called a Step-down transformer.

Note:
Transformers also are prone to flux losses. The two coils are placed closed to each other. Also, the transformation ratio is related to the currents in the two coils but in numerator comes the secondary current and in denominator comes primary current. Also, since transformation ratio is a ratio, it is a dimensionless number.