Electric Resistance and OHM's Law — Formula Sheet

I = Q/t ; instantaneous I = dQ/dt

j = I/A ; I = j.A cos(theta) ; I = ∫ j.dA

I = neAv_d ; j = nev_d

a = F/m = -eE/m ; v_d = a*tau = -(e*tau/m)*E

mu_e = v_d/E = e*tau/m

tau = lambda/v_rms

R = V/I

Ohm's law: V directly proportional to I when physical conditions are constant

G = 1/R

1 ohm = 1 volt/ampere

v_d = (e*tau/m)*(V/l)

R = (m/(n e^2 tau))*(l/A)

rho = m/(n e^2 tau)

I = Q/t and I = dQ/dt.

1 A = 1 C/s = 6.25×10^18 electrons per second.

v_d = -(eτ/m)E.

Electric current is the rate of flow of charge

I = Q/t.

Current density is the current per unit cross-sectional area at a point: j = I/A.