electricity

drift velocity

-eE J / m

acceleration

-eE / m

mobility

vd/ E

I

n e A vd

I

A n e M E

I

n e’2 A E J/m

R

ml / A n e'2 E

rho

m / n e’2 J

temperature dependence of resistivity

rh = rho (1+@ (t-to) )

temperature dependence for metals

positive

temperature dependence for insulators and semi conductor

negative

temperature dependence for alloys

positive but small

J

I/A

sigma

1/rh

G

1/R

E

J/sigma

temperature of superconductivity

-196

power

VI , I’2R , V’2/R

energy

VIT , I'2R, V’2T/R

V

E - Ir

r (internal resistance)

E - V / I

series emf

n E

series resistance

nr + R

series I

n e/ nr + R

parallel emf

Emf

parallel resistance

r/n + R

parallel I

nE / r + nR

kcl

sum of current,meeting at jn is 0

kvl

sum of potential drop and emf is 0