Unit 2.1) Conduction of Electricity Flashcards
What is electric current, state its units.
The rate of flow of charge. It is measured in amps A where A = Cs^-1
Give the symbol equation relating charge, current and time(equation for current relating charge and time)?
I=ΔQ/Δt
Q=charge(Coulombs)
I=current(Amps)
t=time(seconds) where Δ is the change
In electricity what does e represent. What are the units of e
e represents the electron. e is the elementary charge -ie. a proton has a charge +e, an electron has charge -e
the units are Coulombs
Give two examples of possible charge carriers
Electrons- in metals.
Ions- in electrolytes
Does current flow from negative to positive
No. Conventional current is the ‘flow of positive charge’- it is in the opposite direction to the movement of the electrons in the circuit.
How can you measure the current in a circuit
You can measure the current in a circuit with an ammetre connected in series with the component
What is meant by ‘mean drift velocity’
The average velocity of the charge carriers due to the applied electric field.
It has to be an average because they’re often moving randomly in all directions
Equation for free electrons?
I=nAve
I= current
A=cross sectional area of conductor
n=number density of charge carriers,
e=the elementary charge, v = mean drift velocity
What are the units of number density of charge carriers in the equation relating current and drift velocity
m^-3
What is the unit of charge?
The unit of charge is coulomb(C).
Electron’s charge in terms of coulomb?
An electrons charge is a very small fraction of a coulomb.
Charge can flow through certain materials called?
Conductors.
What does the area under an I-t graph give(current-time)?
Charge flow?
What is the mechanism of conduction in metals?
The drift of free electrons.
