Question

Name the switch/switches to be closed so as to light all the three lamps.

A. 2 and 3
B. 1 and 3
C. only 2
D. 1 and 2

Answer 1

In this question there are closed and open circuits. And Always remember an electric circuit works only when the circuit is closed.

Complete step by step answer:
You can see in the question to light up all the lamps. You have to close the path for all the lamps. You have two options to light up all the lamps.
(1) close all the switches. i.e. close switches 1, 2, and 3. Then all paths are complete from lamps to the voltage source.
(2) close switches 2 and 3 that will complete the path for all the lamps from the source. No need to close switch 1.
Then, Option A switch 2 and 3 are correct.
Option B is incorrect because it doesn’t light up all the lamps. When you close switch 1 and 3 then, the lamp near switch 2 will not light up.
Option C is incorrect because it doesn’t close the path from source to lamps.
Option D is incorrect because it doesn’t light up all the lamps. It only lights up a lamp near switch 2.

So, the correct answer is “Option A”.

Note:
The current always flows through the circuit which has the least resistance. The path from the source to the application should be connected.