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Transcript
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