Question

A 220 V input is supplied to a transformer. The output circuit draws a current of 2.0 A at 440 V. If the ratio of output to input power is 0.8, then the current drawn by primary winding is ______.

Options

• 3.6 A

• 5.0 A

• 2.5 A

• 2.8 A

Answer 1

A 220 V input is supplied to a transformer. The output circuit draws a current of 2.0 A at 440 V. If the ratio of output to input power is 0.8, then the current drawn by primary winding is 5.0 A.

Explanation:

Given, input voltage supplied to transformer,

V₁ = 220 V

Current at output circuit of transformer,

i₂ = 2A

V₂ = 440 V

`("Output power"("P"_2))/("Input power" ("P"_1)) = 0.8`

`=> ("V"_2"i"_2)/("V"_1"i"_1) = 0.8`

`(440 xx 2)/(220 xx "i"_1) = 0.8`

`4/"i"_1 = 0.8`

`=> "i"_1 = 4/0.8 = "5A"`

Hence, current drawn by the primary windings is 5 A.