Question

A transformer increases an alternating e.m.f. from 220V to 880V. If primary coil has 1000 turns, the number of turns in the secondary coil are ______.

Options

• 1000

• 2000

• 3000

• 4000

Answer 1

A transformer increases an alternating e.m.f. from 220V to 880V. If primary coil has 1000 turns, the number of turns in the secondary coil are 4000.

Explanation:

The turns ratio of a transformer is given by the formula:

`V_s/V_p = N_s/N_p`

Where,

• V_p​ = Primary voltage = 220V
• V_s​ = Secondary voltage = 880V
• N_p = Number of turns in the primary coil = 1000
• N_s​ = Number of turns in the secondary coil (to be found)

`N_s = N_p xx V_s/V_p`

`N_s = 1000 xx 880/220`

N_s = 1000 × 4

N_s = 4000