In a transformer the relation between the input frequency and the output voltage on secondary winding is _____.

A. Same
B. Increases
C. Decreases
D. Increases and decreases with time

Answer 
A. Same

Explanation
  • The relation between the input frequency and the output voltage on secondary winding are the same. 
  • A transformer is a static device, that has voltage fluctuation in its primary winding and secondary winding at a constant frequency due to the mutual induction property.
  • If the supply frequency of a transformer increases, the secondary output voltage of the transformer increase.

The EMF Equation Of A Transformer is given by

$E = 4.44fBNA$

where
E = the voltage in the winding either primary or secondary,
f = frequency
B = flux density in the core
N = number of turns on the winding
A = Cross area of the core

  • A transformer is designed for some constant parameters like frequency. 
  • So if the frequency increases, the secondary voltage or emf increases. But with high frequency, there is an increase in transformer losses like core loss and conductor skin effect. 
  • Also with high frequency, the magnetizing current becomes low and with low frequency the magnetizing current becomes high.
  • The higher the input frequency, the higher will be the rate of change of magnetic flux, which results in higher induced EMF
  • Frequency ~ Rate of Change of Magnetic Flux ~ Induced EMF.

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