Question
What is transformer? What is its transformation ratio ?
✓
Answer
Transformer : It is the most important electrical appliance used to convert electric power at low voltage and high current to electric power at high voltage and low current and vice versa. It works on the principle of mutual induction, hence it works for alternating current only and not for direct current. It was first devised by Josheph Henry.
Transformers are of two types: (i) Step-up transformer. (ii) Step-down transformer.
Step-up transformer convert power at low voltage and high current to power at high voltage and low current.
Step-down transformer convert power a high voltage and low current to power at low voltage and high current.
Transformation Ratio : In a transformer the ratio of number of turns in its secondary coil to the number of turns in its primary coil is called its transformation ratio and is denoted by r.
Hence.
$r = \frac{\text{Number of turns in secondary coil}}{\text{Number of turns in primary coil}}$
$r=\frac{N_{s}}{N_{p}}$
Since step-up transformer Ns > Np and in step-down transformer NS < NP hence the value of r is greater than 1 for step-up transformer and is less than 1 for step-down transformer.
Transformers are of two types: (i) Step-up transformer. (ii) Step-down transformer.
Step-up transformer convert power at low voltage and high current to power at high voltage and low current.
Step-down transformer convert power a high voltage and low current to power at low voltage and high current.
Transformation Ratio : In a transformer the ratio of number of turns in its secondary coil to the number of turns in its primary coil is called its transformation ratio and is denoted by r.
Hence.
$r = \frac{\text{Number of turns in secondary coil}}{\text{Number of turns in primary coil}}$
$r=\frac{N_{s}}{N_{p}}$
Since step-up transformer Ns > Np and in step-down transformer NS < NP hence the value of r is greater than 1 for step-up transformer and is less than 1 for step-down transformer.
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