Question

two lamps are rated 100w,220vand the other rated 60w, 220 v are collected in parallel to electric mains supply. what current is drawn from the line if voltage is 220 v?

Answer 1

Hey mate....

Here is your answer....

First we will try to calculate the resistances of the two lamps.

The first one has a power of about 100 w, 220 V

As we know P = V²/R

Therefore R = V²/P

Therefore R = (220)²/100 = 484 ohms.

Similarly we can calculate the resistance of the second lamp, it would be (220)²/60 = 806.7 ohms.

Now the lamps are connected parallel therefore the combined resistance would be

(R1 × R2 )/ (R1 + R2)

Therefore combined/equivalent resistance = (484×806.7) / (484+806.7) = 302.5 ohms.

Now the current flowing in the line would be

I = V/R

I = 220/302.5 = 0.73 amperes.

You can ask your doubts in the comment section.

-Mähëshwářàñ