dge fuse in the same way,
through all the switches into the lamp socket, through the
lamp, out of the lamp socket to the fuse gap, across this to
the other wire, and on out of the room.

It goes on from there through more fuses and back to the
dynamo from which the other wire comes.

Test yourself further with the following questions:

1. Where in this circuit is the resistance supposed to be?

2. What happens when you put a good conductor in place of this
resistance if the electricity can get from one wire to the other
without passing through this resistance?

3. Why do we use fuses?

4. What is a short circuit?

5. What makes an electric toaster get hot?

6. Why should you not stick pins through electric cords?

EXPERIMENT 74. Take the fuse wire out of the fuse gap and put
a single strand of zinc shaving in its place. Instead of the
nail plug, screw the lamp into the socket. Do not turn on the
switch that lets the electricity flow through the resistance
wire, but turn on the electricity so that the lamp will glow.
Does the zinc shaving work satisfactorily as a fuse wire?
Now turn the electricity on through the resistance wire. What
happens?

When are the greater number of amperes of electricity flowing
through the zinc shaving? (NOTE. "Amperes" means the amount of
current flowing.) Can the zinc shaving stand as many
amperes as the fuse wire you ordinarily use? Which lets more
electricity pass through it, the lamp or the resistance wire?
Why do electric irons and toasters often blow out fuses? If
this happens at your home, examine the fuse and see how many
amperes (how much current) it will allow to flow through it.
It will say _6A_ if it allows 6 amperes to pass through it;
_25A_ if it allows 25 amperes to pass through it, etc. The
fuse wire across the fuse gap allows about 8 amperes to pass
through before it melts. The zinc shaving allows only about
2. Read the marks on the cartridge and plug fuses. How many
amperes will they stand?

_APPLICATION 60._ A family had just secured an electric
heater. The first night it was used, the fuse blew out.

The boy said: "Let's put a piece of copper wire across the
fuse socket; then there can't be any more trouble."

The father said that they had better get a new fuse to replace
the old one. The old fuse was marked _10A_.

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