4.1 - Electricity: charge and current Flashcards
What is a charge carrier?
A charged particle capable of transferring electric current
What do we mean when we say charge is quantised?
It can only take certain values (always ne)
If n electrons are removed from a neutral object what is its charge?
-ne, positive
What is an electrolyte?
A liquid containing charged ions
What is a metallic conductor?
A material comprising a lattice of positive ions and delocalised electrons that carry electrical current
Which direction does conventional current flow?
from positive to negative
Which direction do electrons flow in a circuit?
From negative to positive
What is an ion?
A non-neutral atom or molecule
what is a cation?
A positively charged ion
what is an anion?
a negatively charged ion
What is an anode?
a positive electrode
What is a cathode?
a negative electrode
how is an ammeter connected?
In series
What is the resistance of an ideal ammeter?
Zero
State Kirchoff’s first law
At any point in a circuit the sum of the currents entering that point is equal to the sum of the currents leaving
What is n in the equation I=nAve and what are its units?
Number density of free charge carriers m^-3
What is A in the equation I=nAve?
cross sectional area of the conductor
What is e in the equation I=nAve?
The elementary charge (1.6*10^-19C)
What is v in the equation I=nAve?
The drift velocity of the charge carriers
What is a conductor?
A material with a large number density of charge carriers ~10^28m^-3
What is an insulator?
A material with a low number density of charge carriers
What is a semiconductor?
A material with an intermediate number density of charge carriers ~10^17m^-3
