Charged particle entering velocity selector

In summary, the conversation discusses a velocity selector, which uses a parallel plate capacitor in an outside magnetic field to select charged particles based on their velocity. The magnetic force on the particles is upwards while the electric force is downwards. When these forces are equal, the particle will move straight through the velocity selector, and the expression v = B/E can be derived for this condition. Particles with a speed larger than v will deflect upwards, while those with a smaller speed will deflect downwards. Finally, an example is given for protons moving through a velocity selector with specific values of electric and magnetic fields, resulting in a speed of 1.5*10^-6 m/s for a proton that is not deflected.
  • #1
britt
32
0
1. The problem
A velocity selector consists of a parallel plate capacitor placed in an outside magnetic field (see figure). Charged particles entering the velocity selector experience an electric and a magnetic force (neglect effects due to gravity). Given is the setup in the figure below (attached)

a) What is the direction of the magnetic force?
b) What is the direction of the electric force?
c) When the two forces are equal the particle will move straight through the velocity selector. Derive an expression for the speed v that fulfills this condition.
d) What happens to particles that have a speed larger than v? What happens to particles that have a speed smaller than v?
e) Protons move through a velocity selector with E = 2.0 · 10^5 N/C and B= 0.30 T. What is the speed of a proton that is not deflected?

Homework Equations

(negatives are supposed to be vectors)
[itex]\overline{}F[/itex]B=q[itex]\overline{}v[/itex] x [itex]\overline{}B[/itex]
[itex]\overline{}F[/itex]e = q[itex]\overline{}E[/itex]
FB=qVB
Fe=qE

The Attempt at a Solution


a) up
b) down
c) qVB=qE
VB=E
V=B/E
d)it will deflect up, it will deflect down
e) v=(.30)/(2.0*10^5)= 1.5*10^-6 m/s
Just want to know if I am doing this correctly
 

Attachments

  • velocity selector.png
    velocity selector.png
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  • #2
It looks correct.

ehild
 

FAQ: Charged particle entering velocity selector

What is a charged particle entering velocity selector?

A charged particle entering velocity selector is a scientific instrument that is used to select particles of a specific velocity from a beam of charged particles. It works by applying both an electric field and a magnetic field to the particle beam, causing particles with the desired velocity to follow a specific path and be separated from particles with different velocities.

How does a charged particle entering velocity selector work?

A charged particle entering velocity selector works by using a combination of electric and magnetic fields to exert forces on charged particles in a beam. The electric field acts to accelerate or decelerate the particles, while the magnetic field acts to deflect the particles. By adjusting the strength and direction of these fields, particles with the desired velocity can be separated from the beam.

What is the purpose of a charged particle entering velocity selector?

The purpose of a charged particle entering velocity selector is to isolate particles with a specific velocity from a beam of charged particles. This is useful in experiments and research where only particles with a certain velocity are needed, and can help scientists better understand the behavior of these particles.

What types of particles can be selected using a charged particle entering velocity selector?

A charged particle entering velocity selector can be used to select almost any type of charged particle, including electrons, protons, and ions. The size and design of the instrument may vary depending on the specific type of particle being studied, but the basic principles of using electric and magnetic fields to select particles of a specific velocity remain the same.

Are there any limitations to using a charged particle entering velocity selector?

While charged particle entering velocity selectors are a useful tool for selecting particles with a specific velocity, they do have some limitations. For example, they may not be able to select particles with extremely high or low velocities, and the precision of the selection may be limited by factors such as the strength and uniformity of the electric and magnetic fields used. Additionally, the instrument may be affected by external factors such as temperature and humidity, which can impact the behavior of the charged particles.

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