A 60 W load is connected to the secondary of a transformer whose primary draws line voltage. If a current of 0.54 A flows in the load, what is the current in the primary coil? Comment on the types of transformer being used.

Answer

A

Explanation

Given, `P_(s)=60 W, I_(s) = 0.54 A`
Current in the primary `I_(p)=?`
Taking line voltage as 220V.
We can write Since,
`P_(L) = 60 W, I_(L) = 0.54A`
`rArr = V_(L)= 60/0.54=110V`
Voltage in the secondary `(E_(s))` is less than voltage in the primary `(E_(p))`.
Hence, the transfomer is step down transformer.
Since, the transformation ratio
`r=V_(s)/V_(p)= I_(p)/I_(s)`
Substituting the values, `(110V)/(220V) = I_(p)/(0.54A)`
On Solving `I_(p) =0.27A`