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Slide 1

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Drift velocity-and how to calculate it.…read more

Slide 2

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Is the movement of electrons through a wire. The
general equation for drift velocity (AS level
anyway) is
I=nAVq…read more

Slide 3

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I= current (in amps)
n = is the number density
A= area of the wire
V= is the drift velocity
q or e= electronic charge (-1.6×10power of -19C
(coulombs)…read more

Slide 4

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The following slides contain some worked
examples and how to calculate them.
In them the equation will be manipulated to find
a certain "part" of it like electron drift velocity.
This is originally for OCR Physics specification
but is suitable for other specifications.…read more

Slide 5

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Q. Find the drift velocity of electrons of wire diameter of 0.32mm, current of
2.4A and where n is 8.5×10 power of -23 M -3
First we write the equation: A= nAVq and see what parts we got. In the
question we have n, diameter of the wire and the charge. Now we can
rearange the equation:
V= I/ nAq but there is one other step- we need to find the area of the wire as
without it its not possible to find the velocity.
Using formula for area : r squared.
Convert to metres which is simply 0.16×10power of -3 m
Now we use area formula :
×(0.16×10 power of -3)squared = 8.04× power of -8 metres squared. Now that
we have the area we can find the drift velocity!…read more

Slide 6

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Now that we have the area its possible to find the drift velocity: consult our
V=I/nAq so we substitute what we got:
V= 2.4A (current)/ (8.5×10 power of 28 ­the n value)×(8.04×10 power of -8 - area
we calculated) ×(1.6×10 power of -19 ­ electronic charge)= 2.2×10 power of -13
So now we have our answer!!!…read more


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