Electromagnetism Flashcards
What is a magnetic field?
It is a region of space within which a current-carrying conductor, a moving charge or a permanent magnet may experience a magnetic force.
What is the direction of magnetic field lines based on?
The direction of the force experienced by the north pole of a magnet.
What is magnetic flux density?
It is the force per unit length of conductor per unit current carried placed at that point at right angles to the field.
or B= F/Il
What is the SI unit of magnetic flux density?
Tesla.
Using the definition of magnetic flux density, find its alternative units.
Magnetic flux density is the force per unit length of conductor per unit current carried placed at that point at right angles to the field. Thus, it is Nm-1A-1 or Wbm-2.
Define Tesla.
It is the flux density in which a long straight wire carrying a current of 1 A normal to the field experiences a magnetic force per unit length of 1 Nm-1
OR
the flux density which a charge of 1 C moving at a velocity of 1 ms-1normal to the field experiences a magnetic force of 1 N.
How is the force that a current carrying conductor placed at angle to a uniform magnetiuc field experiences determined?
F = BILsinθ
The direction of the magnetic force is _____ to the direction of current and the direction of the magnetic field.
Perpendicular
For a charge moving in a magnetic field, how is the force it experiences derived?
F = BQvsin θ
Why does a charge moving parallel to a magnetic field experience no force?
θ = 0
How is F = BQv derived from F = BIl?
I = current = rate of flow of charge = Q/t
In a current-carrying conductor, the charges move with a velocity the same way as if there was no conductor and the charges were moving with velocity v except that the charge does not move in a circular path.
If the charge is negative, the direction of current is _____.
The opposite of the f;ow of charge.
Why does a charged particle move in a circular path when entering a uniform magnetic field?
A magnetic force acts on the charged particle, providing centripetal force for the circular motion.
Note: When drawing the direction of the path of the charge on a magnetic field, draw it like it is moving in circular motion and keep the path within the field.
How is the radius of circular motion of a charge particle in a uniform magnetic field derived?
magnetic force = mass x centripetal acceleration
BQv = mv2/r
making r the subject,
r = mv/BQ
Why does the kinetic energy of a charged particle under the influence of a magnetic field not change as opposed an electric field?
Magnetic force acts perpendicularly to a particle’s velocity ,changing the direction of the velocity but not the magnitude. KE is a scalar and does not take into account direction.
