I'm going to assume your talking about electric current?
In that case, electric current is defined to be the rate of charge passing a particular point.
Charge is given the symbol Q, time t. So if the rate is constant, the current I = Q/t.
In terms of your equation, -e is the charge of one...
I'm now graduated as a secondary school educator, having studied a physics minor at university.
During that time, I didn't go any further than second year physics, studying basic quantum mechanics, thermodynamics, and special relativity.
Much of it I've forgotten, however I keep the basics...
Thank you all for the replies. Seems to have generated discussion. I think we can all agree though that my textbook could have been a bit more clear.
FYI, this is an Australian Year 12 (VCE) textbook.
But my initial displacement is 0 because that's where I started from isn't it? I have attached a crude picture to help explain myself: http://imgur.com/a/LuvLr
This is why I'm now assuming it's talking about the average velocity since the formula is vavg = ∆x / t
My textbook states that "The velocity has the same direction as the displacement".
I feel this statement is incorrect. Keeping in one dimension, let's say that I move in the +ve direction at velocity v for some time t. My displacement is vt which points in the +ve direction. However I then stop...