Question

two lamps one rated 100W at 220V and the other 60W at 220V are connected in parallel to electric mains supply of 220v

Answer 1

Given Question:

Two lamps one rated 100W at 220V and the other 60W at 220V are connected in parallel to electric mains supply of 220V.

Answer:

Your answer is 0.7272 A

Solution:

As we know, $\bf{P = \frac{V²}{R}}$

From the given figure:

$\bf{R_{1} = \frac{V_{1}²}{P_{1}} = \frac{220×220}{60}}$

$\bf{R_{1} = 484Ω}$

$\bf{R_{2} = \frac{V_{1}²}{P_{1}} = \frac{220×220}{60}}$

$\bf{R_{2} = 806.7Ω}$

The equivalent resistance in parallel combination:

$\bf{\frac{1}{R_{eq}} = \frac{1}{R_{1}} + \frac{1}{R_{2}}}$

$\bf{\frac{1}{R_{eq}} = \frac{1}{484} + \frac{1}{806.7}}$

$\bf{R_{eq} = 302.5Ω}$

The current flowing in the circuit:

$\bf{I = \frac{V}{R_{eq}}}$

$\bf{I = \frac{220}{302.5}}$

$\red{\bf{I = 0.7272 A}}$

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Thanks!