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# Electron drift velocity a level physics watch

1. Im having trouble with electron drift velocity,
How would you solve this for example, what's the step by step method
A copper wire has a cross sectional area of 2.0mm^2 &carries a current of of 6.0A
Calculate mean drift velocity of electrons in wire
# density of copper atoms =8.0 x 10^28
Each copper atom provides one conduction electron
Charge on electron: -1.6x10^-19 C

PLEASE GO THROUGH EACH STEP AND EACH FORMULA USED!
2. I=nvQA

I is current in Amps

n is the number density of charge carriers... in a metal you can use the number density of metal atoms multiplied by the number of conduction electrons provided by each atom

v is the drift velocity of the charge carriers

Q is the amount of charge carried by each charge carrier... if the charge carriers are electrons this is the charge per electron

A is the cross sectional area in m2

so you've got to rearrange I=nvQA to get v on it's own on one side of the equals sign... not forgetting to convert any units necessary before you start calculating.

note - the drift velocity is usually lower than you expect when you first start calculating them
3. (Original post by Joinedup)
I=nvQA

I is current in Amps

n is the number density of charge carriers... in a metal you can use the number density of metal atoms multiplied by the number of conduction electrons provided by each atom

v is the drift velocity of the charge carriers

Q is the amount of charge carried by each charge carrier... if the charge carriers are electrons this is the charge per electron

A is the cross sectional area in m2

so you've got to rearrange I=nvQA to get v on it's own on one side of the equals sign... not forgetting to convert any units necessary before you start calculating.

note - the drift velocity is usually lower than you expect when you first start calculating them
n=(8×10^28)×no. Of conduction electrons provided by each electron
But how do I find # conduction electrons?
4. (Original post by SamuraiMK)
n=(8×10^28)×no. Of conduction electrons provided by each electron
But how do I find # conduction electrons?
the equation works off number density, the number per m3

it's a property of the material the conductor is made of - not it's size or shape

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