Magnetism and Electromagnetism Flashcards
What are the 2 types of magnetic pole?
North
South
What are the poles of a magnet?
The places where the magnetic forces are stronger
What is flux density?
The density of the field lines
How can a magnetic compass be used to plot the field around a bar magnet?
Place the bar magnet on a piece of paper
Place the compass at one end of the magnet
On the paper, mark where the point of the compass needle is
Move the compass so the tail of the needle is at the point that has just been marked
On the paper, mark a new point where the needle is
Repeat and connect the marks until the full field is plotted
What does the strenght of a field depend on?
The size of the current and the distance from the wire
What happens when a current carrying conductor is placed in a magnetic field?
It experiences a force
How can a force in a magnetic field be increased?
Increasing current size
Increasing the length of conductor in the magnetic field
Increasing the flux density
What would reversing the direction of either the current or the magnetic field cause the current to do?
Cause the direction of the force to reverse
How is the direction of the force on the conductor found?
Using Fleming’s left hand rule
What is Fleming’s left hand rule?
Hold the left hand so that the thumb, first finger and second finger are all at right angles to one another
Align the first finger so that it points in the direction of the magnetic field, North to South
Rotate the wrist so that the second finger points along the wire in the direction that the current is flowing
The thumb will be pointing in the direction of the force
Why would a current carrying coil in a magnetic field rotate?
The current going up one side of the coil is in the opposite direction to the current coming down the other side
What do loudspeakers and headphones do?
Use the variations in an alternating current to produce sound waves
What is the generator effect?
When a conductor and magnetic field interact, a potential difference can be induced
How might a potential difference be induced?
An electrical conductor moving relative to a magnetic field
A change in magnetic field aaround a conductor
What is the generator effect used in?
Alternators- to generate an alternating current
Dynamos- to generate a direct current
