Ohm’s Law:

V = IR

where V = voltage (V)

I = current (A)

R = resistance (Ω)

Resistance:

R = ρL/A

where ρ = resistivity (Ω·m)

L = length (m)

A = cross-sectional area (m²)

Electric Field:

E = F/q = V/d

where E = electric field (N/C or V/m)

F = force (N)

q = charge (C)

V = potential difference (V)

d = distance (m)

Drift Velocity:

v_d = I/(nAq)

where v_d = drift velocity (m/s)

I = current (A)

n = number density (m⁻³)

A = area (m²)

q = electron charge (1.6×10⁻¹⁹ C)