SP10 Electricity and Circuits Flashcards
What is current?
The flow of electrical charge
What is current measured in?
Amperes (A)
Charge (C) (Coulombs) =
Q =
Current (A) x Time (s)
I x t
Electrical conductors are…?
Materials that allow electric current to pass through them.
All metals are conductors and current in metals is the flow of free electrons.
Explanation = in metal conductors, lots of charges are free to move, these charges are electrons, the current is the flow of these electrons.
Electrical insulators are…?
Materials that don’t allow electric current to pass through them.
Examples of electrical insulators are plastic and glass.
Explanation = there are no free electrons. No charges are free to move and carry a current.
What is potential difference?
The difference in amount of energy that hcarge carriers have between 2 points in a circuit.
What is potential difference measured in?
Volts (V)
Hence, potential difference is also known as voltage.
Energy transferred (J) (joules) =
E =
Charge moved (C) x potential difference (V)
Q x V
Therefore, the p.d. across an electrical component is the amount of energy transferred by that electrical component per unit charge passed.
P.d. of 1 volt =
1 joule of energy being used by 1 coulomb of charge when it flows between 2 points in a circuit.
Ammeters
Measure flow of current that passes through it.
Have to be connected in series with the electrical component who’s current you are measuring.
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Voltmeters
Measure p.d. (voltage) between 2 points in a circuit e.g. betweem 2 points either side of a component
Must be connected in parallel with the 2 points being measured
What is resistance?
Measure of how difficult it is for current to flow through a component
What is resistance measure in?
Ohms Ω
Potential difference =
V =
Current x resistance
I x R
