NCERT - Science

Book: NCERT - Science

Chapter: 12. Electricity

Subject: Physics - Class 10th

Q. No. 2 of In Text Questions-Pg-216

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An electric lamp of 100, a toaster of resistance 50 , and a water filter of resistance 500 are connected in parallel to a 220 V source. What is the resistance of an electric iron connected to the same source that takes as much current as all three appliances, and what is the current through it?

The combined resistance R of three resistors (or electrical devices) R1 R2 and R3, connected in parallel is given by the formula:

Here, Resistance of electric lamp, R1 = 100

Resistance of toaster, R2 = 50

Resistance of water filter, R 3 = 500

Putting these values of R1 R2 and R3 in the above formula, we get:

Thus, the resistance of electric iron will also be 31.25.

Now, Potential difference, V= 220 V

Current, I =?

Thus, the current passing through the electric iron is 7.04 amperes.


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