Three switches and a closed door


You are in a room that has three switches and a closed door. The switches control three light bulbs on the other side of the door. Once you open the door, you may never touch the switches again.
How can you definitively tell which switch is connected to each of the light bulbs?


REVEAL THE ANSWER

Turn on the first two switches. Leave them on for five minutes. Once five minutes has passed, turn off the second switch, leaving one switch on. Now go through the door. The light that is still on is connected to the first switch. Whichever of the other two is warm to the touch is connected to the second switch. The bulb that is cold is connected to the switch that was never turned on.


Cracked that riddle, did you? Fantastic work! But the fun doesn’t stop here. Ready to tackle another? Find more riddles to solve right…


  • Whose name did the Inspector write down?

    Will Ketchum settled into his chair as Sergeant Zupp came into his office. “‘Have all three arrived, Hans?” he asked.Sergeant Zupp nodded. “They all agreed to come and answer a few questions. The storeowner objected at first, but the cab driver and the painter were willing enough.”‘Inspector Ketchum looked pleased. “If one of them is…

    Crack the Code >>


  • How can you explain

    Carl Jones introduced Roger Smith to his friend as his ‘Uncle Roger’. Roger Smith introduced Carl Jones to his friend as his ‘Uncle Carl’. “If you are uncles to each other,” queried one of the friends, “you must also be nephews to each other.” “That’s correct,” replied Carl. Since there has been no breach of…

    Crack the Code >>


  • What day?

    You have an appointment to meet your friend the logic professor during the winter holidays when she is on vacation. Today is Friday. She has told you to meet her two days after the day before the day after tomorrow. What day does she expect you?

    Crack the Code >>


Embrace the Challenge: Sign Up for Our Riddle Newsletter!


Please enable JavaScript in your browser to complete this form.
Name
Email