Download Q: What happens when a current has too much power?

May 21, 2010
1. What causes static electricity?
2. What are two ways to prevent circuits from
having too much current?
Q: What happens when a
current has too much power?
• When the resistance of a circuit is too low,
the wires carry too much current. When
this happens, the circuit is said to be
overloaded.
– Circuits can be overloaded when too many
appliances are plugged into a single power
source.
Q: What happens when a
current has too much power?
 There are two ways to prevent overloading circuits:
1) Fuse
• A fuse is an electrical device contains a metal
strip that melts (thus opening the circuit) when
the current in a circuit becomes too great.
• Once the metal strip inside a fuse melts, it
must be replaced.
Q: What happens when a
current has too much power?
 There are two ways to prevent overloading circuits:
2) Circuit breaker
• A circuit breaker is a device that protects a
circuit from current overloads by opening the
circuit when the current becomes too great.
• Circuit breaker act like switches and can be
reset to close the circuit again.
Q: What is a short circuit?
• Caused by improper
wiring.
• The current travels
around the resistor,
therefore (often)
overloading the
circuit.
Q: Why do we shock people?
• When you walk across the floor, electric
charges are moving from the floor through
your body, causing an excess of electrons
in your body.
Q: Why do we shock people?
• When you come in contact with something
that doesn’t have an excess of charge, the
charges move from your body to the other
thing.
• Called static electricity.
– “Static”- means unmoving. The electrons just
hang out in your body for a while.
How Stuff Works Video
• VanDeGraff Generator