An electric lamp of 100 Ω a toaster of resistance 50 Ω, and a water filter of resistance 500 Ω

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?

Solution:

Resistance of electric lamp (R₁) = 100 Ω

Resistance of toaster (R₂) = 50 Ω

Resistance of water filter (R₃) = 500 Ω

Potential difference of the source, V = 220 V

Since all the resistance are in parallel then the equivalent resistanceR of the circuit will be 

 

All the three given appliances are drawing 7.04 A of current.

Therefore, current drawn by an electric iron connected to the same source of potential 220 V = 7.04 A

Let   Rʹ be the resistance of the electric iron. According to Ohm’s law,

 

 

Therefore, the resistance of the electric iron is 31.25 Ω and the current flowing through it is 7.04 A.