Electrostatics-determining velocities

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Homework Help Overview

The discussion revolves around a theoretical problem involving a charged particle in a magnetic field, where participants are tasked with determining the velocity of the particle given its charge, mass, and the magnetic field strength. The problem lacks visual aids and additional context, leading to various interpretations of the requirements for finding the velocity.

Discussion Character

  • Exploratory, Assumption checking, Conceptual clarification

Approaches and Questions Raised

  • Participants discuss the relationship between the charge, magnetic field, and mass in the context of the equation qvB=ma. There is uncertainty about how to isolate velocity from this equation. Some participants question the validity of the problem, suggesting that a velocity cannot be determined solely from the given parameters without additional information, such as the radius of the particle's circular motion.

Discussion Status

The discussion is ongoing, with participants exploring different interpretations of the problem. Some have provided hints and guidance regarding the nature of acceleration and the role of circular motion, while others express skepticism about the problem's feasibility without further details.

Contextual Notes

There is mention of missing information, specifically the radius of the circular path, which is implied to be necessary for solving the problem. Additionally, participants are navigating the implications of using the correct formula for acceleration in this context.

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My physics teacher gave us a problem about a charged particle; it was a theoretical problem, so there weren't any figures. He said that the charge of the particle, the value of the magnetic field, and the mass was known. Then he said that we needed to find the velocity of the charged particle. I am not sure how to do this!


i used the formula: qvB=F and set that equal to ma=F. From this i got qvB=ma, however, I am not sure how to simplify the equation so that I am only solving for velocity in terms of q,B, and m! please help!
 
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plutolover said:
My physics teacher gave us a problem about a charged particle; it was a theoretical problem, so there weren't any figures. He said that the charge of the particle, the value of the magnetic field, and the mass was known. Then he said that we needed to find the velocity of the charged particle. I am not sure how to do this!


i used the formula: qvB=F and set that equal to ma=F. From this i got qvB=ma, however, I am not sure how to simplify the equation so that I am only solving for velocity in terms of q,B, and m! please help!

you need the correct formula for a!
 
I don't think this is a good problem. You cannot get the velocity from the charge, mass, and magnetic field. If thee is a velocity, the charge would go in a circle forever (I think)
 
barryj said:
I don't think this is a good problem. You cannot get the velocity from the charge, mass, and magnetic field. If thee is a velocity, the charge would go in a circle forever (I think)

You think right.

So why can't the charge go around in a circle forever with a certain constant velocity (actually speed)?

BTW the problem omitted that you also need the radius of the circle.
 
rude man said:
you need the correct formula for a!

isn't a just delta v over time? then I would have time as an unknown variable. what do you mean by correct formula?
 
plutolover said:
isn't a just delta v over time? then I would have time as an unknown variable. what do you mean by correct formula?

v is a vector. A vector can change its magnitude, its direction, or both, with time.

So the hint for you is that v changes its direction but not its magnitude v. If the particle moves in a circle with let's say constant speed v, what is |dv/dt|? Hint: think centrifugal acceleration.

Note that I use bold characters for vectors and regular for their magnitudes.
 
rude man said:
Hint: think centrifugal acceleration.

Mmm.. centripetal?
 

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