Question

two lamps one rated 100 w at 220V and the
other 40W at 220v are connected parallel to 220v
mains supply calculate the current drawn from
the supply line

Answer 1

Answer:

Explanation:

For combinations of devices in parallel, the total power of the devices just add up thus total power of combination will be: 100+40 =140W

thus total current drawn: I=P/V = 0.64A

Answer 2

Answer:

I_series = 0.30 A

I_parallel = 1.36 A

Explanation:

Given :

Two lamps power as 100 W and 200 W at 220 V.

We have resistance formula :

R₁ = 220 × 220 / 100 = 484 Ω

R₂ = 220 × 220 / 200 = 242 Ω

In series combination :

R_net = 484 + 242 Ω

= > 726 Ω

We have ohm's law :

V = I R

I = 220 / 726 A

I = 0.30 A

( ii ) In parallel combination :

1 / R_net = 1 / 484 + 1 / 242 Ω

R_net = 484 / 3 Ω

Given :  V = 220 V

I' = 220 / 484 × 3 A

I' = 1.36 A