Charges in Magnetic Fields Flashcards
How are magnetic fields produced?
By moving charged particles.
What is the unit for magnetic field strength B?
Tesla (T)
What are crosses and dots indicative of?
Crosses - into the page
Dots - out of the page
What is a monopole?
1 pole
What is a dipole?
2 poles
Does a charged particle create its own magnetic field?
A moving charged particle creates its own magnetic field. If the charged particle enters an external magnetic field, the two fields will interact resulting in a force being exerted on the moving particles
What is the formula for force on a moving charge in a magnetic field?
F = qvB = qvBsin(theta)
When is the force max/min when velocity is per/par to B?
Force is max when velocity is perpendicular to the magnetic field. Force is zero when the velocity is parallel to magnetic field.
What is the right hand palm rule?
Fingers = direction of magnetic field, thumb = direction of the velocity of the charged particle and the palm will point to direction of the force experienced by the charge.
What do you have to do when finding negative charge with RHPR?
Must flip the force as it is opposite direction to the positive charge
When will a charged particle undergo uniform circular motion?
The velocity is perpendicular to the magnetic field and force, hence the force will act towards the centre (theta = 90)
What is the derivation of the radius of UCM of a charged particle?
Fc = Fb
mv^2//r == qvBsin(theta = 90)
r= mv/qB
What is the formula for the mass?
m = rBq/v
Compare and contrast the trajectories of charged particles in electric and magnetic fields.
In an electric field, both the magnitude and direction of the force remains constant (down) hence particle will travel in a parabola. In the magnetic field, the direction constantly changes to act perpendicularly to the velocity an hence the particle travels in a circle.
What happens to accelerating changes over time?
Emit electromagnetic radiation and hence lose kinetic energy and slowly spiral inwards towards the centre.
How does a helical motion of charges occur?
If the velocity is not perpendicular to magnetic field, the motion can be analysed by breaking the components into parallel and perpendicular. Velocity (II) is always constant, as there is not force, and no accl due to it being in the same direction as the field. Velocity (per) would be qvB, and this will result in a helix shape.
What is the distance between each loop called?
Pitch
What is the formula for acceleration of a charged particle in a magnetic field?
a = F/m = qvBsin(theta)//m
What is the formula for orbital period?
T = 2pim//qB
