(I'm lucky to have a computer ... It was only through the miracle of
modern digital technology that I was able to flip your photo right-
side-up to where I could read it.)
Here's how to figure out things like this:
The circle on the left side labeled ' G ' is the Generator or battery
that powers this whole circuit and all the devices in it. In order for
any device to work, you need to be able to set your pencil down at
the top of the Generator, and find a path through the circuit and
through that device, where current can flow all the way around to
the bottom of the Generator. If you ever come to an open switch,
then current stops there, and you have to find another way through.
If the path you found takes you back to the bottom of the generator but
it doesn't go through one of the devices, then that device doesn't work.
Look at the picture. If you open switch S-4, then Device-4 can't work,
because current can't go through it from one end of the Generator to
the other end. But all of the other devices still work.
I can see 2 ways to turn off Device-3 with a single switch ... either
open switch S-5, or else open switch S-1. Unfortunately, I think
either way will shut off all 5 devices.
