5. Electricity (Wip) Flashcards
Define ‘electric current’
The rate of flow of electric charge in a circuit.
What is currents SI unit?
Amps or amperes.
What is the equation symbol of current?
The letter I.
Define ‘Potential Difference’
Work done per unit charge flowing between two points in a circuit.
What is potential difference’s SI unit?
Volts or voltage.
What is the equation symbol of voltage?
The letter V.
Define ‘resistance’.
The opposition of a component to the flow if electric current through it.
What is resistance’s SI unit?
Ohms represented by Greek letter omega, Ω.
What is the equation symbol of ohms?
The letter R.
What does Ohm’s law state?
’ A conductor at constant temperature’s current will be directly proportional to its voltage.’
What is the equation for Ohm’s law?
V=IR
What is an Ohmic conductor?
Any conductor where the current is directly proportional to the voltage.
What does the VI graph of a resistor look like?
https://www.elevise.co.uk/uploads/9/8/0/2/98021560/screenshot-2021-08-09-at-09-00-37_2.png
What does the VI graph of a filament lamp look like?
https://www.elevise.co.uk/uploads/9/8/0/2/98021560/screenshot-2021-08-09-at-09-00-37_2.png
What does the VI graph of a diode look like?
https://www.elevise.co.uk/uploads/9/8/0/2/98021560/screenshot-2021-08-09-at-09-00-37_2.png
What is resistivity?
A property of a material which determine how much resistance is has to the flow of charge of electrons.
Why does resistivity occur?
Free electrons in a wire collide with ions resulting in a loss of kinetic energy upon collision causing electrical heating.
Example: https://cdn.savemyexams.com/cdn-cgi/image/w=640,f=auto/uploads/2020/09/9.3.1-Electrons-and-resistance.png
What is the relationship between temperature and resistance?
The greater the temperature the higher resistance due to electrons colliding with vibrating ions for conductors which obey ohms law.
What is a thermistor?
A non-ohmic conductor which when temperature is higher, resistance decreases.
