• Support PF! Buy your school textbooks, materials and every day products Here!

Motion of a charged particle in magnetic field

  • #1

Homework Statement


A particle of charge -q and mass m enterd magnetic field B at A with speed v1 at an angle alpha and leaves the field at C with v2 at angle beta.Then,

a)alpha=beta
b)v1=v2
c)particle remains in the field for time t=(2m(pi-alpha))/qB
d)All of these

Please see image below

https://ibb.co/iLMrie

Abhimessi10fig.jpg



Homework Equations


F=qvB


The Attempt at a Solution


Really dont know how to do it.Tried resolving components.
 

Attachments

Last edited by a moderator:

Answers and Replies

  • #2
kuruman
Science Advisor
Homework Helper
Insights Author
Gold Member
8,727
2,136

Homework Statement


A particle of charge -q and mass m enterd magnetic field B at A with speed v1 at an angle alpha and leaves the field at C with v2 at angle beta.Then,

a)alpha=beta
b)v1=v2
c)particle remains in the field for time t=(2m(pi-alpha))/qB
d)All of these

Please see image below

https://ibb.co/iLMrie

Homework Equations


F=qvB


The Attempt at a Solution


Really dont know how to do it.Tried resolving components.[/B]
Resolving components will not get you very far. Other than F=qvB, what else do you know about the motion of particles in magnetic fields? Can you draw the path connecting the entry and exit points of the particle?
 
  • #5
Resolving components will not get you very far. Other than F=qvB, what else do you know about the motion of particles in magnetic fields? Can you draw the path connecting the entry and exit points of the particle?
I dont know to draw the path for particles entering at general angles.just the case when angle=90, 0, and in between.
 
  • #6
kuruman
Science Advisor
Homework Helper
Insights Author
Gold Member
8,727
2,136
I dont know to draw the path for particles entering at general angles.just the case when angle=90, 0, and in between.
OK. What kind of path do you get in these cases? Why is the path like that and like something else?
 
  • #7
OK. What kind of path do you get in these cases? Why is the path like that and like something else?
Because of magnetic force acting as centripetal force?
 
  • #8
kuruman
Science Advisor
Homework Helper
Insights Author
Gold Member
8,727
2,136
Because of magnetic force acting as centripetal force?
Yes., and if the magnetic force is centripetal, what kind of path does the particle describe for as long as the force remains centripetal?
 
  • #9
Yes., and if the magnetic force is centripetal, what kind of path does the particle describe for as long as the force remains centripetal?
Depends on the angle velocity makes with the magnetic field.On a general basis i can say circular-kinda motion.
 
  • #10
kuruman
Science Advisor
Homework Helper
Insights Author
Gold Member
8,727
2,136
Depends on the angle velocity makes with the magnetic field.On a general basis i can say circular-kinda motion.
Look at your drawing. The magnetic field is directed into the screen and the velocity vector is in the plane of the screen. What do you think the angle between the magnetic field and the velocity is?
 
  • #11
Look at your drawing. The magnetic field is directed into the screen and the velocity vector is in the plane of the screen. What do you think the angle between the magnetic field and the velocity is?
The sin alpha component of velocity is only perpendicular
and cos alpha would remain same?
 
  • #12
kuruman
Science Advisor
Homework Helper
Insights Author
Gold Member
8,727
2,136
The sin alpha component of velocity is only perpendicular
Imagine placing your index finger perpendicular to the face of an analog clock and keeping it fixed. What is the angle between your finger and the seconds hand at any time t? The seconds hand is like the velocity vector that changes direction in the plane of the screen and your index finger is like the magnetic field the direction of which is fixed.
 

Related Threads on Motion of a charged particle in magnetic field

  • Last Post
Replies
1
Views
1K
  • Last Post
Replies
8
Views
511
  • Last Post
Replies
8
Views
5K
Replies
3
Views
2K
Replies
15
Views
2K
Replies
13
Views
26K
  • Last Post
Replies
1
Views
6K
  • Last Post
Replies
1
Views
1K
Replies
6
Views
3K
Replies
26
Views
29K
Top