Chapter 22 - Electric fields Flashcards
Where does an electric field act?
Around any charged body. Greater the charge, stronger the field strength
What do electrical conductors contain a lot of?
Free electrons
What are free electrons?
Electrons which move about inside the metal and are not attached to any one atom
What happens when a charged conductor is connected to the earth?
Charge neutralised by electrons transfer between the conductor and the earth
What do electrically insulating materials not contain?
Free electrons
What is earthing?
When electrons move to or from the earth to balance charges on charged objects
What can a gold leaf electroscope be used for?
Used to detect charge
What happens if a charged object is in constact with the metal cap of the electroscope?
Some of the charge of the object transfers to the electrocope. Therefore, the gold leaf and the metal stem which is atttracted to the cap gain the same type of charge and the leaf rises beacause it is repelled by the stem.
What do field lines of an electric field show?
Path a free positive test charge follows when near a body with a much bigger charge.
Draw a field 2 oppositely charged objects would create
Draw the field a point object near an oppositely charged plate would create
Draw the field two oppositely charged plates create
What is the defintion of electric field strength (E)?
What is the unit?
electric field strength at a point in the field is defined as the force per unit charge on a positive test charge placed at that point
What is a test charge?
Charge with a magnitude so small that placing it a point has a negligible effect on the field around that point
What is the equation for electric field strength when a positive test charge is acted on by force F due to the elctric field?
E = F/Q
Decribe the field lines between 2 parallel plates?
- Parallel to each other
- At right angles to the plates
- From the positive plate to the negative plate
What kind of field acts between two parallel plates?
Uniform
What is the equation for electric field strength in a uniform field?
E = V/d
d = seperation