2.1 Conduction of electricity Flashcards
What is the law of conservation of charge?
The net charge in a system remains constant (provided charges cannot enter or leave).
What is an electrical conductor?
A material, or piece of material, through which a charge can flow.
Which particles have a positive charge?
Protons
Which particles have a negative charge?
Electrons
Which symbol is used to denote charge?
Q or q
What is the SI unit of charge?
coulomb (C)
What is the notation for an electron’s charge?
-e
What is the notation for an proton’s charge?
e
What does e= (when referring to the charge of a proton)?
e=1.602 * 10^-19 C
Define electric current
The electric current through a conductor is the rate of flow of charge: the charge passing per unit time through a cross section of the conductor
Equation for electric current
I = ΔQ/Δt
Symbol for Electrical current
I
Unit for electrical current
ampere (A) or C s^-1
What is drift velocity?
The drift velocity is the flow velocity that a particle, such as an electron, attains due to an electric field.
What is the typical thermal speed for an electron at room temperature?
10^5 m s^-1
What is the symbol for drift velocity?
v
Derive I=nAve
Over 1 second, electrons with drift velocity V travel through a wire of cross sectional area A. Distance Vt (t = 1) multiplied by area A gives a volume AV. This volume multiplied by the electron density of the material n, gives the number of electrons in volume V, nAV. The charge in the volume of material is found by multiplying the number of electrons by the elementary charge e, nAVe. This is the amount of charge passing through the wire every second, or current I. Therefore, I = nAVe
What instrument is used to measure current?
Ammeter
How does current change around a series circuit?
It doesn’t - it is the same all around.
