Electricity (Physics) Flashcards
What are conductors? Give an example.
Materials that allow the movement of electrons. Aluminum, salt water.
What are insulators? Give an example.
Materials that prevent the movement of electrons. Rubber, pure water.
What is the law of electric charges?
Objects that have like charges will repel, objects that have opposite charges will attract.
What is charging by friction? Give an example.
When two neutral materials are rubbed or touch, the electric charges are transferred from one object to the other. Ex. when hair is brushed, the atoms in the comb gain electrons and the atoms in the hair lose electrons because human hair has a higher charge tendency than the comb.
What is charging by conduction?
Charging a neutral object by contact with a charged object. Ex. A neutral metal sphere becomes charged by conduction when brought in contact with a negatively charged bar. Some of the electrons are transferred from the bar to the sphere, resulting in an overall negative charge on the sphere.
What is charging by induction? Give an example.
Charging a neutral object by bringing a charged object close to but NOT touching. Ex. A negatively charged balloon is brought near a neutral wall, causing an induced charge separation in the wall. The wall becomes temporarily charged by induction.
What is grounding?
Removing excess charge by transferring electrons between the object and the ground (Earth).
When would you use static electricity?
In photocopying, air filters, automotive paints, paint sprays, theatres, operating rooms, dust testing and printers.
What is the formula for calculating resistance?
Resistance/potential difference = voltage ÷ current
What is the formula for finding power?
Power = Energy ÷ time
How to calcuate percent effiency?
output ÷ input x 100%
How to calculate electrical energy consumption?
Enegry consumed = Power x time
How to calculate cost to operate?
Cost to operate = power used x time x cost of electricity
What do ammeters measure? Where is it placed?
Current. In the circut.
What do voltmeters measure? Where is it placed?
Potential difference. In parallel with load or energy source.
