Flashcards in ⭐️Topic SP10/SP11 - Electricity, static electricity and circuits Deck (93)
What are the rules of current in a series circuit?
-it’s the same everywhere
-it reduces as more components are added
What’re the rules of potential difference in a series circuit?
Potential difference is shared between components so will reduce as more components are added
What are the current rules in a parallel circuit?
-current entering and leaving the circuit is the same
-current splits at a junction
-the more branches, the more current on each branch
What is the rules for potential difference in a parallel circuit?
Potential difference is the same on each branch and is shared between the components of each branch
Why do metals conduct electricity?
Because metals have few electrons in their outer shell which are weakly attracted to the nucleus and so there are many free electrons that can be pushed by the voltage from a battery
Where do electrons move to in a circuit?
Towards the positive terminal as they are negatively charged
What is the conventional direction of current?
Where in a circuit, the conventional current direction goes from the positive terminal to the negative terminal of the battery
What is current measured in? What with?
Amps using an ammeter
How do you use an ammeter?
You connect it in series to measure the current passing through a component or circuit
When current moves through a circuit does it change?
No. current leaving the positive terminal of a battery is the same as current arriving at the negative terminal as it’s conserved
What does current do at each junction of a parallel circuit?
It splits but total amount entering junctions is the same as total amount leaving
What does potential difference do in a circuit?
It ‘pushes’ the current around an electric circuit. It allows electrons to flow when applied across a component
The bigger the potential difference across a component...
The bigger the current
What is needed for a current to flow?
The circuit must be closed and must contain a good source of potential difference like a cell or battery
What is potential difference measured with and what’s the unit?
With a voltmeter and it’s in volts
How do you use a voltmeter?
You connect it in parallel to measure the potential difference across a component or circuit
What is charge? What is charge measured in?
The rate of the flow of current and is measured in coulombs (C)
What is 1 coulomb?
The charge that passes a point in a circuit when there is a current of 1 amp for 1 second
What is the current? What does it do?
The flow of electrons and so moves charged particles
What does the size of the current in a circuit tell you?
How much charge flows past that point each second
How can you calculate charge? Give units
Charge (C) = current (A) x time (s)
Also written as
Q = I x t
How is energy transferred in a circuit with a cell and a lamp starting from the cells store of energy?
1. The cell has a store of energy
2. Energy is transferred to the charge
3. They charge can now transfer energy to the components in the circuit ; it has a store of potential energy (this means it has the potential to transfer energy to other components in the circuit)
3. Energy is transferred from the charge as it moves through the lamp
4. The lamp transfers energy to the surroundings by heating and by light
What is the potential difference of a cell?
The amount of potential energy the cell transfers to each coulomb of charge
How can you calculate energy transferred using charge and potential difference? Use units
Energy transferred (J) = charge moved (C) x potential difference (V)
Also written as:
E = Q x V
What is resistance and what is it measured in?
A measure of how hard it is for the current to flow measured in ohms
What does it mean is some wires and components have a large resistance?
They they need a larger potential difference to produce current through them than others
How can you calculate potential difference in terms of resistance and current? use units
Potential difference (V) = current (A) x resistance (Ω)
Also written as
V = I x R
What happens to total resistance of a circuit when resistors are connected in series and explain?
The total resistance is increased because the pathway becomes harder for current to flow through.
How is potential difference distributed across resistors in series?
It’s shared between resistors but not always equally but resistors with higher resistances will have a greater potential difference