P3.1 - Static and Charge Flashcards
What is Charge?
a property of matter like mass
Why are atoms neutral?
they have an equal amount of protons and electrons
how do you produce static electricity?
1) Rub two insulators together
2) Electrons are transferred between both insulators
3) One object object ends up with a surplus of electrons, other a surplus of protons
4) which creates a corresponding charge difference
How do you discharge a charged object?
+ connect it to something that allows the charge to flow
ie. a piece of metal or when you touch a car door
What is a spark?
A flow of charge (when a object becomes discharged)
What is a gravitational field?
a region around a mass where another mass experiences a force
Describe field lines
+ are like elastic bands, will stretch when a charged object is placed in the field lines
+ force on an object will be in the direction that causes field lines to shorten
+ close = strong field
What is current?
The rate/flow of charge
What are the conditions for a current to flow?
+ need a cell or battery/ power supply
+ current everywhere in a closed loop is the same
Which way does a current flow?
From the positive terminal of the battery to the negative
What is the equation to calculate charge?
charge flow (C) = current (A) x time (S)
What is charge measured in?
Coulombs (C)
What is current measured in?
Amperes/amps (A)
how do objects become charged?
lose or gain electrons
what happens when there is difference in charge (positive vs negative)between two objects?
potential difference occurs (rapid transfer of charge), known as static electricity
what is required for an uncharged object to become charged by induction?
electrons to move around the object
what is the direction of an electric field?
the direction that a positively charged object would move at that point in the field
what is a conventional current?
The model where current flows from positive to negative terminals on a circuit(opposite to electron current flow)
what are small currents measured in?
miliAmps (mA)
what are currents of home appliances measured in?
mA (so 1000Amps is a lot, 1kA)
why do electrons flow in the direction they do?
negative -> positive
because they’re negatively charged
in what kind of objects does static electricity build up?
only in insulators
what are the conditions needed for charge to flow?
- source of potential difference
- closed circuit
Acetate rod - electron movement
From the acetate rod to the cloth, leaving the rod positively charged
Polythene rod - electron movement
From the cloth, to the polythene rod, leaving the rod negatively charged
