Topic 1... Electricity Flashcards
(47 cards)
What does Ohm’s law state?
‘The resistance of a conductor is directly proportional to the P.D across two points.’
What does directly proportional mean?
Straight line through(0,0) , two things are directly proportional if they have a consistent ratio
What does potential difference mean?
The difference of electrical potential between two points.
What is current?
The flow of electric charge (electrons)
What is resistance?
Anything that slows down the flow of charge.
What are the three rules for drawing circuits?
1) Straight lines for wires.
2) Battery at top of the diagram.
3) No components on corners.
What is a diode?
A component that allows current to flow in only one direction.
What is a resistor?
An electrical component that restricts the flow of electric current.
What is a variable resistor?
Allows more control over the current by changing the amount of resistance.
What is a thermistor?
A temperature sensor.
What is an LDR (Light Dependent Resistor)?
A light sensor (detects light levels).
Where do the components lie in parallel circuits?
On multiple loops.
Current in a parallel circuit?
The current splits and travels down the different loops.
P.D/ voltage in parallel circuit?
Voltage across the components stays the same along each loop.
Resistance in a parallel circuit?
Resistances in parallel circuits reduce the total resistance in the circuit.
The total resistance = the sum of 1/the resistances
Where are the components in a series circuit?
On one loop.
Current in series circuits?
Current is the same at all points in the circuit. More components causes the current to drop.
Voltage/ P.D in a series circuit?
Voltage/ P.D splits in a series circuit. The total voltage/ P.D is the sum of the voltages of the voltage across each component.
Resistance in series circuits?
Total resistance is the sum of the resistances of the individual components.
What do V-I graphs show?
How the current varies as you change the P.D.
What is the V-I graph of different resistors like?
At a constant temperature the current is directly proportional to the P.D, this follows Ohm’s law.
Different resistors have different resistances.
What is the V-I graph of a filament lamp like?
As the temperature of the filament lamp increases, the resistance increases. The current is not directly proportional to the potential difference.
What is the V-I graph of a diode like?
A diode has a very high resistance in one direction, current can only flow in the other direction.
What is the V-I graph of a thermistor like?
At low temperatures, resistance of thermistor is high and there is little current. At high temperatures, the resistance is low and there is more current.
