In this chapter of AS/A-level Physics, you will learn about electricity.
Electricity
Current is the rate of flow of charge --> depends on rate and time
Q= Charge in coulombs and t= Time in seconds
- Coulomb is a unit of charge --> amount of charge that passes 1 second if the current is 1 ampere (A)
- You can measure the current using an ammeter --> always attached in series
Potential Difference
When it comes to AS/A-level Physics, potential Difference is the energy per unit charge
- P.d or voltage is the work done per unit charge moved
- Measured with a voltmeter --> always in parallel
- Volt = The p.d across a component is 1 volt when you convert 1 joule of energy moving 1 coulomb of charge through the component 1V = 1JC-1
Resistance
- The amount of current for a particular p.d depends on the resistance of the components
- Resistance measures how difficult it is to get a current to flow R inAS/A-level Physics
- Component has 1 Ω if a p.d of 1V makes a current of 1A flow through it
- For Ohmic conductor, R is a constant --> most metals obey ohms law
- If R is constant, then 𝐼 𝖺 𝑉
Semi conductors
Semi conductors --> used in sensors
- Not as good conductors as metals --> less charge available
- IF energy is supplies to semi conductor then more charge carries can be released --> excellent sensors for detecting changes in their environment: Semi conductors can be Thermistors or Diodes
- As temp increases more electrons break free
Thermistors
Resistance in thermistors depend on heat/temperature in AS/A-level Physics
- NTC thermistors --> negative temperature coefficient
- Resistance decreases as temperature increases
Has same graph as filament for I/V
- Warming thermistor gives more electrons energy to escape their atoms meaning more charge carriers available so resistance decreases
Diodes
- Only allow current to flow in one direction
You now can handle it.
