IGCSE/GCSE/O & A Level/IB/University Student Forum

Qualification => Subject Doubts => GCE AS & A2 Level => Sciences => Topic started by: Superstrings on November 11, 2009, 09:48:13 am

Title: Physics help :(
Post by: Superstrings on November 11, 2009, 09:48:13 am

question is from may june 05, multi-choice, #32

A copper wire of cross sectional area of 2mm^2 carries a current of 10A.
How many electrons pass through a given cross-section of the wire in one second?

A. 1.0 x 10^1
B. 5. x 10^6
C. 6.3 x 10^19
D. 3.1 x 10^25

I have no idea how to do this :(

Title: Re: Physics help :(
Post by: Superstrings on November 11, 2009, 10:03:59 am

Nvm resolved >_>

Title: Re: Physics help :(
Post by: astarmathsandphysics on November 11, 2009, 11:29:31 am

One mo

Title: Re: Physics help :(
Post by: astarmathsandphysics on November 11, 2009, 11:35:57 am

Q=It
ne=I81
n=I/e=10/1.6*10^-19=6.3*10^19
I think thay want you to change it to unit csa ie scale up from 2mm^2 to 1m^2 which is a sclae factor of 50000 ans =e