Question

A 12 V, 60 W lamp is connected to a 220 V AC supply using an ideal transformer. Find the primary current.

Options

• 2.7 A

• 3.7 A

• 0.37 A

• 0.27 A

Answer 1

0.27 A

Explanation:

As the transformer is ideal,

P_output = P_input = 60

⇒ I_p V_p = 60

⇒ I_p = \[\frac {60}{V_p}\]

= \[\frac {60}{220}\] = \[\frac {3}{11}\]

= 0.27 A