Question 2:
An electric lamp of 100 Ω, a toaster of resistance 50 Ω, and a water filter of
resistance 500 Ω 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?
Answer:
Resistance of electric lamp, R1 = 100 Ω
Resistance of toaster, R2 = 50 Ω
Voltage of the source, V = 220 V
These are connected in parallel, as shown in the following figure.
Let R be the equivalent resistance of the circuit.
According to Ohm’s law,
V = IR
I = V/R
Where,
Current flowing through the circuit = I
7.04 A of current is drawn by all the three given appliances.
Therefore, current drawn by an electric iron connected to the same source of
potential 220 V = 7.04 A
Let R’ be the resistance of the electric iron. According to Ohm’s law,
V = IR’
Therefore, the resistance of the electric iron is 31. 25 Ω and the current flowing
through it is 7.04 A.
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