Magnetic Fields Flashcards
What does it mean if the field lines are closer together in a magnetic field?
The field is stronger at that point.
What does the direction of a magnetic field line tell you?
The force felt if a North pole was put in that place.
Which direction is a magnetic field going if it is resembled by a dot on the page?
Out of the page.
Which direction is a magnetic field going if it is resembled by a cross on the page?
Into the page.
What does your thumb represent in Fleming’s left hand rule?
Force felt.
What does your first finger represent in Fleming’s left hand rule?
Field lines.
What does your second finger represent in Fleming’s left hand rule?
Current.
What is the magnetic flux density?
Force per unit current per unit length, on a current-carrying wire in a magnetic field.
Define the Tesla (T).
Magnetic field strength required to produce 1N of force for a 1A and 1m long wire.
How does a split-ring commutator work in a motor?
When the rotating coil is vertical, there is a gap in the split-ring commutator which stops the current, meaning there are no forces acting on the coil.
The momentum from the previous rotation allows for the coil to continue to rotate and the brushes can regain contact with the commutator again.
Describe the path of a charged particle in a magnetic field.
Circular path.
What is the equation for the radius of the circle that a charged particle experiences in a magnetic field?
r = mv / BQ
How do the particles in a cyclotron accelerate?
P.d. across ‘dees’ switches when the particle is inside one, so it becomes attracted to the other side and accelerates across the gap between the ‘dees’.
What is the equation for the time a particle spends inside a ‘dee’ in a cyclotron?
t = m x pi / BQ
What is magnetic flux?
The amount of magnetic field that passes through a certain area of material.
Flux = BA
