PAG 11.3 Determining the Magnetic Field of a Magnet Flashcards
What is the magnitude of the force experienced by a current-carrying wire placed in a magnetic field?
F = BIL
State the safety precautions that should be taken when working with wires carrying high currents.
Wires carrying high currents will get very hot, so you must avoid touching the wire throughout the experiment. The power supply should be turned off when not required in order to reduce the heating effect.
What rule can be used to determine the force on a current-carrying wire in a magnetic field?
Fleming’s Left Hand Rule
Explain how to apply Fleming’s Left Hanf Rule
Thumb - Force
First finger - Magnetic Field (B)
Second finger - Current (I)
What direction do magnetic field lines point in?
Magnetic field lines point from North side to the South side
In what direction does conventional current flow?
Conventional current flow is from the positive terminal of the source to the negative terminal.
In this experiment, in what direction is the force on the wire due to the magnetic field?
The force on the wire is upwards, but since the wire is clamped in place, a downwards force will be exerted onto the mass balance.
What device can be added to the circuit to allow the current to be varied?
A rheostat can be added in series into the circuit.
How is the reading from the mass balance converted into a force value?
F = mg
Describe the graph that should be formed when plotting the mean mass reading against current
Straight line through the origin, since mass and current are directly proportional
How can the magnetic flux density be obtained from a graph of mean mass against current?
Gradient is M/L
B = gradient x g/L
where mass is in kg
What length measurement should be used for calculations?
Length of the magnets should be used since this will equal the length of the wire that experiences the magnetic field
Why is the length used in F=BIL not always equal to the length of the wire?
Length refers to length of wire in the magnetic field.
It does not include the extra length outside the field
What is ignored when considering the length of wire experiencing the magnetic field?
Edge effects of the magnet are ignored since these regions are negligible and not uniform
What unit is used for magnetic flux density?
Tesla
