top button
Flag Notify
Connect to us
    Facebook Login
    Site Registration Why to Join

    Get Free Puzzle Updates

Facebook Login
Site Registration

How can you determine with which of the three switches the light bulb can be switched on?

+3 votes
554 views

A light bulb is hanging in a room. Outside of the room, there are three switches, of which only one is connected to the lamp. In the starting situation, all switches are 'off' and the bulb is not lit.If it is allowed to check in the room only once to see if the bulb is lit or not (this is not visible from the outside), how can you determine with which of the three switches the light bulb can be switched on?

posted Apr 27, 2014 by anonymous

Share this puzzle
Facebook Share Button Twitter Share Button Google+ Share Button LinkedIn Share Button Multiple Social Share Button

1 Solution

+1 vote

Step 1. Switch on any bulb for 1 min lets say first one.
Step 2. Switch on the second bulb and go inside. there will be three cases :

case 1. If bulb is on then second switch is correct one.
case 2. If bulb is off then touch bulb it if it is hot then first one was the correct switch.
case 3. if both above cases are not true then third one the right switch.

solution Apr 28, 2014 by Amit Kumar Pandey



Similar Puzzles
0 votes

A one armed surgeon with a hand wound needs to operate on three patients. The surgeon only has two gloves.
How can he operate on the three patients without risking exchange of fluids? (Remember he only has one arm so he only needs to wear one glove at a time.)

0 votes

On a circle there are 2014 light bulbs, 2 are ON, and 2012 are OFF. You can choose any bulb and change the neighbor's state from ON to OFF or from OFF to ON. Doing so, can we get all 2014 light bulbs on ? If yes, How?

0 votes

You have 21 jars with you. Out of them, 7 are filled with water, 7 are half-full with water and 7 are empty.
How will you distribute the jars among three people such that each one of them gets the equal number of jars and equal amount of water?

+1 vote

You have a flashlight that takes 2 working batteries. You have 8 batteries but only 4 of them work.

What is the fewest number of pairs you need to test to guarantee you can get the flashlight on?

+1 vote

enter image description here

There are 13 caves arranged in a circle. There is a thief hiding in one of the caves. Each day the the thief can move to any one of of the caves that is adjacent to the cave in which he was staying the previous day. And each day, you are allowed to enter any two caves of your choice.

What is the minimum number of days to guarantee in which you can catch the thief?

Note: Thief may or may not move to adjacent cave. You can check any two caves, not necessarily be adjacent. If thief and you exchange your caves, you will surely cross at some point, and you can catch the thief immediately.

Contact Us
+91 9880187415
sales@queryhome.net
support@queryhome.net
#470/147, 3rd Floor, 5th Main,
HSR Layout Sector 7,
Bangalore - 560102,
Karnataka INDIA.
QUERY HOME
...