Current produced by a single charge moving in a circlular motion

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Homework Help Overview

The problem involves calculating the magnetic field produced by an electron moving in a circular path around a proton, as described in Niels Bohr's model of the hydrogen atom. The focus is on understanding the relationship between the motion of the charge and the resulting magnetic field.

Discussion Character

  • Conceptual clarification, Assumption checking, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss the calculation of current from a moving charge, questioning the application of formulas for magnetic fields from straight wires versus circular loops. There is confusion regarding the derivation of the current and the time taken for a complete orbit.

Discussion Status

The discussion is ongoing, with participants exploring different interpretations of the current calculation. Some have expressed clarity on certain points, while others continue to seek understanding of the underlying concepts and relationships.

Contextual Notes

Participants note potential misunderstandings regarding the application of formulas and the assumptions made about the motion of the charge. There is an acknowledgment of the need to revisit foundational concepts related to current and magnetic fields.

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Homework Statement



In Niels Bohr's 1913 model of the hydrogen atom an electron circles the proton at a distance "R" with a speed "v". Compute the magnitude of the magnetic field that this motion produces at the location of the proton.

Homework Equations



Bio Savart

B = mu*I / 2R = mu * q * (v/2piR) / 2R


The Attempt at a Solution



The solution is stated above in the relevant equations section.

There are some misunderstandings I have as to how they arrived at the equation for the current.

First the magnetic field given by an infinite wire should be mu*I/2*pi* r but is shown as it is above without the pi in the denominator. Further, I thought that the moving charge should have a current that is equivalent to its velocity, charge, and cross sectional area ( I = nqvA ), but that is not what is correct. I feel as if I'm missing the big pink elephant in the room that is related to the period of the of charge or something. Can someone give me some help?
 
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I'm sorry the magnetic field in the center of a current loop is B = mu*I / 2*R. I guess I don't understand how the current is being calculated.
 
Current is given by
I = Q/t
So current is due to the charge of one electron, moving in a circular loop.
To get t in the equation, how much time does it take the charge to make a complete orbit around the loop?

p.s. also, note the formula for a long straight wire does not apply here, since the current is in the form of a circular loop.
 
Redbelly98 said:
Current is given by
I = Q/t
So current is due to the charge of one electron, moving in a circular loop.
To get t in the equation, how much time does it take the charge to make a complete orbit around the loop?

p.s. also, note the formula for a long straight wire does not apply here, since the current is in the form of a circular loop.

Geez I don't know why I couldn't figure it out. That makes so much sense and its so simple. I think I just need to go over the material a lot more and try to understand the concepts better. Thanks a lot I appreciate the help.
 

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