Atoms are basic particles from which all matter is made up
What is an atom made up of?
Protons, neutrons and electrons
What are the masses of protons, neutrons and electrons?
1 1 and 1/2000 respectively
Materials that allow electricity to flow through them are called . . .
electrical conductors eg.metal
Materials that do not allow electricity to flow through them are called . . .
electrical insulators eg.plastic
When can an insulator become charged?
When there is static electricity
When does electric charge (static) build?
When electrons (which have a negative charge) are rubbed off one material or onto another
The material that recives electrons becomes...
The material that loses electrons becomes...
Give three examples of common electrostatic phenomena
any three from lightning, charges on synthetic fabrics, shocks from car doors or negatively charged balloons
Explain how a laser printer works
an image of the page to be copied is projected onto an electrically charged plate (+ve) Light causees charge to leak away leaving an electrostatic impression on the page. The impression attracts specks of black powder (of opposite charge) and heat is used to fix the final image
Explain how electrostatic painting works
The car panel is given a negative charge and sprayed with positively charged powder paint. The paint spreads out because the positive charges repel each other and are attracted to the negatively charged panel
give an example of when unsafe static needs to be discharged
filling aircraft fuel tanks
what is earthing
earthing allows constant safe discharge to occur, to equalise the imbalance of electrons between the two objects. When earthing occurs electrons flow from one body to the other to remove the imbalance
What does electric current need to flow?
A compete circuit
The flow of electrons in a circuit is from . . .
-ve to +ve (although we draw the current flow in a circuit from positive to negative)
How do you work out charge?
Charge (coulombs) = Current (amperes) X Time (seconds)
Cells and batteries are sources of ______ current
What is direct current?
Current that flows in one direction only
What is an alternative name for voltage?
when current is flowing _____ is transferred from the cell to the circuit components
the greater the potential difference the greater the _____ ____ and the greater the _____
electron flow and current
Potential difference is the energy (in joules ) that is transferred per unit charge (in coulombs) that passes through a source or component Formula...
Volt = Joule/coulomb
Current is measured . . .
in amperes (amps) using an ammeter
one millamp = ____ amps
0.001 (one thousandth of)
At any point in a series circuit the rate of electron flow will be __ ___ so the current and ammeter readings will be __ ___
ammeters must be connected in
voltmeters must be connected in
In a circuit the current leaving the battery or the cell is the same as ___ ____ ____
the current returning . Because electrons that make the current cannot leave the circuit.