Send the link below via email or IMCopy
Present to your audienceStart remote presentation
- Invited audience members will follow you as you navigate and present
- People invited to a presentation do not need a Prezi account
- This link expires 10 minutes after you close the presentation
- A maximum of 30 users can follow your presentation
- Learn more about this feature in our knowledge base article
Do you really want to delete this prezi?
Neither you, nor the coeditors you shared it with will be able to recover it again.
Make your likes visible on Facebook?
You can change this under Settings & Account at any time.
Moving Charges in Magnetic Fields
Transcript of Moving Charges in Magnetic Fields
An electric current is the result of a flow of charge. Therefore, if a current in a conductor
experiences a force due to the presence of a magnetic field, then so should a single charge as
it moves through a field.
This is the principle used by particle accelerators like the one at CERN.
The direction of movement of a beam of negative electrons in a magnetic field can be predicted using the right-hand motor rule, but remember that electrons move in a direction opposite to that of conventional positive charges, so you must point your extended thumb in the opposite direction to the travel of the electron beam.
The size of the force exerted is found to depend on:
the size of the charge C in coulombs
the velocity of the charges in m/s
the strength of the field B, in Tesla.
Recall that the maximum force produced on a current-carrying conductor is:
In the diagram, the charged particles are protons of mass 1.67 × 10^–27 kg. They enter the magnetic field of strength B = 3.0 × 10^–2 T at a velocity of 2.5 × 10^5 m s–1.
(a) the force acting on the protons
(b) the radius of curvature of their path in the field.
And current can be expressed as I=q/t
This gives us:
Because l/t=v (distance over time)
The force on the moving charge will be acting constantly to change its direction of travel. In fact, the force is always directed at right angles to the instantaneous direction of travel. This is centripetal motion. Thus, if a moving charge enters a magnetic field it will be curved into a circular path of travel. If the strength of the field is strong enough the charged particle may be constrained to move in a completely circular path within the field and may never escape.
Note that this effect will occur for all charged particles, not just simple electrons. This
effect has very useful practical applications, especially where charged particles or ions
do Qs 18,19,20 on page 572