Module 4.1 Electricity (charge and current) Flashcards
What is electromotive force?
-The amount of energy given to each coloumb of charge when the chemical energy of the cell is converted into electrical energy
-Measure in volts
What needs to be there in order for a circuit to work effectively
-An electromotive force
-A closed path or complete circuit
What is conventional current and electron flow?
-(Conventional current)When electricity was first discovered they believed that current flowed from positive to negative
-(Electron flow) electrons flow from negative to positive terminal
What is the equation for charge?
Q=IT
Q=charge
I=current
T=time
Why are metals such good conductors? and why are electrolytes also good conductors?
-The flow of charge is made up of electrons, metals have delocalised electrons which can drift slowly across the wire
-Electrolytes are also good conductors as they have positive and negative ions which can carry charge
What is Kirchhoff’s law?
-Charge is always conserved so the sum of charges flowing into a junction must be equal to the sum of charges leaving, this law is also true for current.
What is a coulomb?
-The unit of charge is defined as the quantity of charge that passes a fixed point when 1amp of current is flowing
What is elementary charge(e)?
-The charge of an electron (-1.6*10^-19) or a proton(positive value)
-when a particle becomes charged it contains a whole number of electrons so their net charge must be a multiple of e
What is the formula for the mean drift velocity?
V=I/nAe
V: mean drift velocity
I: current
n: number of free electrons per unit volume
A: cross sectional area
e: charge of an electron
Compare n for semiconductors, conductors and insulators
Insulators: very little/close to zero of n (number of electrons per unit volume)
Semiconductors: have values of n between insulators and conductors
Conductors: have very high values of n
