Unit 2 Variables

q

charge: a property of an object (C)

n

number of fundamental charges

e

fundamental charge: charge of a proton or electron (1.6 × 10^-19)

I (i)

current: flow of objects with charge (A or C/s)

V

electric potential: energy that a hypothetical coulomb of charge would have at that spot (V or J/C)

ΔV

electric potential difference: the change in energy a hypothetical coulomb would undergo between two spots (V or J/C)

ε

EMF: electromotiveforce: ideal potential difference of a battery (V)

R

resistance (Ω)

l

length of a resistor (m)

A

cross-sectional area of a resistor (m²)

p

resistivity: how resistive a material is (Ωxm)

o

conductivity: how conductive a material is; inverse of resistivity(Ωm)-1

P

power: rate of change of energy (W or J/s)

delta V/delta r

the average electric field between two points in space is equal to the electric potential difference the two points divided by the distance between the two points; electric fields point from hight to ow potential (V/m)

C

capacitance: the ability of a system to store electric charge (F)

K

dielectric constant (Dielectric of air is 1.00)

A

plate area (m²)

d

plate separation (m)

Uc

energy stored in the electric field of capacitor (J)

Vd

drift velocity of electrons inc current (m/s)

J

current density = current / cross-sectional area (A/m²)