AP Mag Problem: 2.0keV Positron in 0.10T Field - Find Period, Pitch, Radius

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In summary, a 2.0 keV positron with a velocity vector making an angle of 89 degrees with a uniform magnetic field B of 0.10 T has a period of 3.6e-10 sec, pitch of 1.63e-4 m, and radius of 1.48e-3 m when projected into the field. The kinetic energy of the particle can be used to calculate its speed, and the magnetic force acting on it is equal to the centripetal force in its helical path. The pitch is the angle at which the particle's path winds up, similar to a spring hanging vertically. This problem can be solved by resolving the velocity vector into horizontal and vertical components.
  • #1
Physicsisfun2005
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A 2.0 keV positron is projected into a uniform magnetic field B of 0.10 T with its velocity vector making an angle of 89 degrees with B. Find
a. the period
b. the pitch p
c. the radius of the helix


We have never done a problem similar to this in class so I'm am not sure where to start...
 
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  • #2
Here's a hint:

[tex] \v{F} = Q ( \v{E} + \v{u} x \v{B} ) = \frac{m v^2}{r}[/tex]
 
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  • #3
The 2.0 keV is the kinetic energy of the particle, from which you can get the speed (but remember to convert to joules).
 
  • #4
ahhh...mag force = centripital force
 
  • #5
Physicsisfun2005 said:
ahhh...mag force = centripital force
Oui!
Ja!
Yes!
 
  • #6
"pitch"? :confused:
 
  • #7
Brad Barker said:
"pitch"? :confused:
If you look at a spring that is hanging vertically, you can see that it winds "up" to the right or to the left with a certain angle to the horizontal. This angle is the pitch. THe path of a charged object traveling through a magnetic filed will also be a helix (like a spring).
 
  • #8
we went over it in class and i got the correct answers :smile:

if u want to know here they are:

a. period is 3.6e-10 sec.
b.pitch is 1.63e-4 m
c.radius is 1.48e10-3 m

Was easy once I figured that i needed to resolve the velocity vector in horizontal and vertical components :rofl:
 

1. What is the purpose of the AP Mag Problem?

The AP Mag Problem is a simulation used to study the motion of a positron (a positively charged particle) in a magnetic field. It helps scientists understand how charged particles behave in this type of environment.

2. What is the significance of the 2.0keV energy and the 0.10T magnetic field in the problem?

These values were likely chosen to represent a realistic scenario, as they are within the range of energies and magnetic fields that can be found in nature. They also allow for easy calculations and analysis.

3. How do you calculate the period, pitch, and radius in this problem?

The period can be calculated using the formula T = 2πm/qB, where m is the mass of the particle, q is its charge, and B is the magnetic field strength. The pitch can be found using the equation p = mv/qB, where v is the velocity of the particle. The radius can be calculated using the formula r = mv/qB.

4. What factors affect the motion of the positron in this problem?

The motion of the positron is primarily affected by its initial energy, the strength of the magnetic field, and the mass and charge of the particle. Other factors such as the shape and orientation of the magnetic field can also play a role.

5. How is the AP Mag Problem relevant to real-world applications?

The AP Mag Problem can help scientists understand and predict the behavior of charged particles in various magnetic fields, which has many practical applications. This includes the development of technologies such as particle accelerators, MRI machines, and plasma fusion reactors.

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