There are 3 bulbs in a closed room, with their switches to the outside One ofthe bulbs is fused - Physics - Magnetism and Electricity

Question

There are 3 bulbs in a closed room, with their switches to the
outside One ofthe bulbs is fused Now the situation given is: -you
can only go inside the room once -You must figure out which switch
belongs to the fused bulb -You can switch on any one switch when
you enter the room

Satyendra Singh · Accepted Answer

Dear
Student,
Please find below
the solution to the asked query:

Follow the following steps:

Switch on one of the switches and keep it like that for about
10 minutes and then switch it off This will heat up a non fused
bulb if it is connected to the first switch
Now switch on a different switch and go inside the room
CASE I: Now when you enter the room and a
light is glowing then, that switch which is on at the moment does
not belongs to the fused bulb Now touch the bulbs the one which is
hot will be connected to the first switch , and the cold one will
be the fused bulb and will be connected to the third switch
CASE II: You enter the room and one of them is
glowing and the other two are cold then the first switch is
connected to the fused bulb as then only the first switch would not
have turned on any of the bulb and the two non glowing bulbs are
cold
CASE III: Now, when you enter and if in case
non of the bulbs are glowing when you enter the room then, the
switch which is presently on is the one that belongs to the fused
bulb As there can only be one explanation for the switch to be on
and not glowing any of the bulbs

Hope this
information will clear your doubts about (Magnetism and
electricity)
If you have any
more doubts just ask here on the forum and our experts will try to
help you out as soon as possible
Regards
Satyendra
Singh

There are 3 bulbs in a closed room, with their switches to the outside. One ofthe bulbs is fused. Now the situation given is: -you can only go inside the room once. -You must figure out which switch belongs to the fused bulb. -You can switch on any one switch when you enter the room.