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PFStudent
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Homework Statement
12. A strip of copper [itex]{150{\textcolor[rgb]{1.00,1.00,1.00}{.}}{\mu}m}[/itex] thick and [itex]{4.5{\textcolor[rgb]{1.00,1.00,1.00}{.}}mm}[/itex] wide is placed in a uniform magnetic field [itex]{\vec{B}}[/itex] of magnitude [itex]{0.65{\textcolor[rgb]{1.00,1.00,1.00}{.}}T}[/itex], with [itex]{\vec{B}}[/itex] perpendicular to the strip. A current [itex]{i = 23{\textcolor[rgb]{1.00,1.00,1.00}{.}}A}[/itex] is then sent through the strip such that a Hall potential difference [itex]V[/itex] appears across the width of the strip.
Calculate [tex]V[/tex]. (The number of charge carriers per unit volulme for copper is [tex]8.47{\times}{10^{28}}[/tex] electrons/[tex]m^{3}[/tex]).
Homework Equations
[tex]
q = n_{e}e, {\textcolor[rgb]{1.00,1.00,1.00}{.}}{\textcolor[rgb]{1.00,1.00,1.00}{.}}{\textcolor[rgb]{1.00,1.00,1.00}{.}}{n_{e}} = \pm1, \pm 2, \pm 3,...,
[/tex]
e [itex]\equiv[/itex] elementary charge
[tex]
e = 1.60217646 {\times} 10^{-19}{\textcolor[rgb]{1.00,1.00,1.00}{.}}C
[/tex]
[tex]
{n_{e}} = {\pm}N, {\textcolor[rgb]{1.00,1.00,1.00}{.}}{\textcolor[rgb]{1.00,1.00,1.00}{.}}{\textcolor[rgb]{1.00,1.00,1.00}{.}}{N} = 1, 2, 3,...,
[/tex]
[tex]
{N_{V}} = \frac{n_{e}}{V}
[/tex]
[tex]
{n_{e}} = {N_{V}}{V}
[/tex]
[tex]
{N_{V}} = {\frac{BI}{{\Delta{V}}{le}}}
[/tex]
Where, [tex]{\Delta{V}}[/tex] is the Hall potential difference.
The Attempt at a Solution
This seems like a straight forward problem, here is how I worked through it.
[tex]
{\Delta{V}} = {\frac{BI}{{N_{V}}{le}}}
[/tex]
Let [itex]I[/itex] = current, [itex]{\Delta}{V} = V[/itex], and [itex]\left({\frac{N}{V}}\right)[/itex] be the number of charge carriers per unit volume. So, since we're dealing with electrons,
[tex]
{N_{V}} = -{\left({\frac{N}{V}}\right)}
[/tex]
Where,
[itex]{\left({\frac{N}{V}}\right)} = {{8.47}{\times}{10^{28}}}[/itex] electrons/[itex]{m^{3}}[/itex]
However, since they gave me two distances: thickness ([itex]{t}[/itex]) and width ([itex]{w}[/itex]); which one is [itex]{l}[/itex]?
I thought at first, it was the width because isn't that how the Hall potential difference is defined, as the potential across the width of a strip?
The book used the thickness, so I am wondering why?
Any help is appreciated.
Thanks,
-PFStudent
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