Electricity Flashcards
What is the definition of current
Current is charge flow per unit time (I=Q/t) It is the movement of charged particles which are most commonly electrons
How does current behave in a series circuit
Current is constant everywhere in the circuit due to the conservation of charge
What is the unit for charge, current, and potential difference
Coulombs, Amperes and Volts
Which way does conventional current flow
Conventional current flows from positive to negative however the actual charge from the electrons moves negative to positive
What happens to current in a parallel circuit
Current splits at every branch but the sum at any point must be a constant and recombine at some point due to the conservation of charge as current is NOT used up, namely charge isn’t used up
What is the definiton of voltage
Potential difference is the difference in electrical potential energy at two points in a circuit, it is defined as the work done per unit charge meaning a volt is defined as a JC^-1. This is because when a charge passes a point, or current flows, through a device, the electrical energy carried by the charged particles often in the form of kinetic energy is converted to other forms of energy such as heat or light, so work is done and a difference in electrical potential energy is created, meaning a voltage
What happens to voltage in a series circuit
In series, voltage is used up at each component such that the sum of voltages must equal the total voltage from the supply
What is resistance
Resistance is defined as being R=V/I
What is ohms law
Ohms law states that V∝I in an ohmic conductor or in other words V=IR where R is the constant of proportionality
Name an Ohmic conductor and two non ohmic conductors
A constant resistor and then a filament lamp and a diode
What is the IV graph of a resistor
A straight line passing through the origin
What is the IV graph of a filament lamp
A curved line flattening further away from the origin and steepening as it gets nearer
What is the IV graph of a diode
A straight line up from voltage breakdown up to around 0.7V where the current spikes near vertically as it starts to conduct
What is the purpose of a diode and how can it be protected
A diode is a forward-biased conductor which means it only allows current to flow one way and at a certain voltage, say at 0.7V it will start to conduct current freely, anything lower, it won’t conduct and anything higher it may damage it. This can be prevented by adding a resistor into the circuit which will limit the amount of current allowed to flow.
If e, the unit charge or charge on an electron is 1.6x10^-19 C how many electrons are in one coulomb and what consequences does this have?
You would so 1\e so around 6.24x10^18 electrons per coulomb as there is 1.6x10^-19 coulombs per electron so the reciprocal would give the value we want
