Section 5: Electricity & Circuits Flashcards
What is electric current?
The rate of flow of charge
What allows current to pass through metals?
Delocalised electrons
What happens to current if there is no source of potential difference?
No current flows
What happens to current if there is a source of potential difference?
Current flows
What is resistance?
Anything that slows down the flow of charge
What does current through a component depend on?
The components resistance and potential difference across the component
What happens to current if resistance increases?
The greater the resistance, the smaller the current
What can be used to change the current in a circuit?
Variable resistor
What is potential difference?
The energy transferred per unit of charge that passes between two points in a circuit
What is another name for potential difference?
Voltage
What is the unit of measure for charge?
Coulombs, C
What is the unit of measure for current?
Amperes, A
What is the unit of measure for resistance?
Ohms, Ω
What is the unit of measure for potential difference?
Volts, V
What is 1 volt equal to?
1 J/C OR 1 joule per coulomb
What happens to current in an open switch?
Current doesn’t flow
What happens to current in a closed switch?
Current flows
What are the three different current-potential difference graphs?
- Fixed resistor at a constant temp
- Filament lamp
- Diode
What happens in a fixed resistor at a constant temperature graph?
Current is directly proportional to potential difference SO resistance doesn’t change
What type of graph is the fixed resistor at a constant temperature graph?
Linear
(Straight line going through origin)
What happens in a filament lamp graph?
Current increases SO temperature of filament increases SO resistance increases
What does a filament lamp graph look like?
Non linear
Plateaus at bottom and top but straight line in the middle
What happens in a diode graph?
High resistance in one direction SO current only flows in the other direction
What does a diode graph look like?
Non linear
Line starts straight then its gradient rapidly increases
What components are the ones with a changing resistance when current through them varies?
Filament lamp
Diode
LDR (light dependent resistor)
Thermistor
CIRCUIT SYMBOLS MADE ON IN PERSON FLASHCARDS
What does resistance depend on in a LDR (light dependent resistor)?
Light intensity
When in there lower resistance in a LDR (light dependent resistor)?
When there’s a brighter light
When in there higher resistance in a LDR (light dependent resistor)?
When there’s a dimmer light
What does resistance depend on in a thermistor?
Temperature
When in there lower resistance in a thermistor?
Hotter temperatures
When in there higher resistance in a thermistor?
Cooler temperatures
What do resistance graphs look like for LDRs?
Resistance on y axis
Light intensity on x axis
The line goes downwards
The gradient is steep but gradually lowers