Question

A transformer consisting of 300 turns in the primary and 150 turns in the secondary gives output power of 2.2 kW. If the current in the secondary coil is 10 A, then the input voltage and current in the primary coil are ______.

Options

• 220 V and 20 A

• 440 V and 20 A 

• 440 V and 5 A

•  220 V and 10 A

Answer 1

A transformer consisting of 300 turns in the primary and 150 turns in the secondary gives output power of 2.2 kW. If the current in the secondary coil is 10 A, then the input voltage and current in the primary coil are 440 V and 5 A.

Explanation:

Power output (V₂I₂) = 2.2 kW 

∴ V₂ = `(2.2"kW")/((10"A"))` = 220 volts

∴ Input voltage for step-down transformer

`"V"_1/"V"_2="N"_1/"N"_2=2`

`"V"_"input"=2xx"V"_"output"`  

= 2 × 220 

= 440 V

Also `"I"_1/"I"_2="N"_2/"N"_1`

∴ I₁ = `1/2xx10`

= 5 A