Good Morning,(adsbygoogle = window.adsbygoogle || []).push({});

The equations under investigation:

Electrons: J = enμE + eD(dn/dx)

Holes: J = epμE - eD(dp/dx)

n or p = concentration of electrons or holes respectively

D = diffusion constant

μ = mobility

The question in mind is as follows:

If holes are traveling in the direction on conventional current, then shouldn't the drift velocity for holes be fully negative, i.e. -epμE - eD(dp/dx)?

I understand by definition that, μ = mobility, is the absolute value of drift velocity (speed) over the electric field hence the direction is lost in the process (or is the same for both a hole and an electron). Therefore, shouldn't the expression for holes written above also technically factor in a negative sign corresponding to the hole drift 'velocity' part of the equation?

Please dispel my confusion lest more holes puncture brain.

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Why is BOTH the electron & hole drift velocity positive?

**Physics Forums | Science Articles, Homework Help, Discussion**