Which switch controls the bulb??
Outside a room there are three light switches. One of switch is connected to a light bulb inside the room.
Each of the three switches can be either ‘ON’ or ‘OFF’.
You are allowed to set each switch the way you want it and then enter the room(note: you can enter the room only once)
Your task is to then determine which switch controls the bulb ??
Set the first switches on for abt 10min, and then switch on the second switch and then enter the room.
Three cases are possible
1.Bulb is on => second switch is the ans
2.Bulb is off and on touching bulb , you will find bulb to be warm
=>1st switch is the ans.
3.Bulb is off and on touching second bulb , you will find bulb to be normal(not warm)
=>3rd bulb is the ans.
This question was asked to me in my Deloitte Interview.It follows as:
1)First ON the first switch. Wait for some time .
2)Now Switch OFF the first switch and ON the second switch.
3)Now go to the room and check if the bulb is glowing (Which means that Second Switch is answer) , or it is warm (which means First Switch is answer) or Neither(Which means third is the answer).
Tip::Never tell the answer directly .Try to tell many approaches and at the end or in middle tell the answer you can try this approach too.
More puzzles to try-
- 3 + 3 = 3 5 + 4 = 4 1 + 0 = 3 2 + 3 = 4 ...Read More »
- Five puzzleFry ship’s pirates have obtained 100 gold coins and have to divide up the loot. The pirates are all ...Read More »
- There are 10 stacks of 10 coins each. Each coin weights 10 gms. However, one stack of coins is defective ...Read More »
- Dr.Willam wants to operate for three different persons who were wounded. But he had only two surgical gloves. There is ...Read More »
- Which clock works best? The one that loses a minute a day or the one that doesn’t work at all?Read More »
- In the gear arrangement, To which one will the needle touch, 1 OR 2Read More »
- A man leaves his house in the morning to go to office and kisses his wife. In the evening on ...Read More »
- Which letter replaces the question markRead More »
- A bridge will collapse in 17 minutes. 4 people want to cross it before it will collapse. It is a ...Read More »
- In a country where everyone wants a boy, each family continues having babies till they have a boy. After some ...Read More »
- A devotee goes to three temples, temple1, temple2 and temple3 one after the other. In front of each temple, there ...Read More »
- There is a perfectly accurate analog watch with hour, minute, and second hands. How many times a day do all three ...Read More »
- Four days are there which start with the letter ‘T‘. I can remember only two of them as “Tuesday , Thursday”. ...Read More »
- Two fathers took their sons to a fruit stall. Each man and son bought an apple, But when they returned ...Read More »
- A farmer is taking her eggs to the market in a cart, but she hits a pothole, which knocks over ...Read More »
- In the middle of the confounded desert, there is the lost city of “Ash”. To reach it, you will have ...Read More »
- Solve this logic sequence puzzle by the correct digit- 8080 = 6 1357 = 0 2022 = 1 1999 = ...Read More »
- Jasmine, Thibault, and Noah were having a night out and decided to order a pizza for $10. It turned out ...Read More »
- A murderer is condemned to death. He has to choose between three rooms. The first is full of raging fires, ...Read More »
- Some numbers are very mysterious. They are all integers. They have more than one digit. If you multiply them with ...Read More »