Magnetism Flashcards
What is the thumb, index and second finger represent in FLH rule?
Thumb - Motion
Index - Direction of the magnetic field
Second - Current
What is the motor effect?
When a wire with a current running through it, cuts through a magnetic field, a force is created
What is the generator effect?
If a wire is in a complete circuit, cuts through a magnetic field, a potential difference is induced
Why does the wire need to move perpendicular to the magnetic field in the generator effect?
Because if the wire moved parallel then no current would be induced
How do you increase the PD produced in the generator effect?
Use stronger magnets
Shape the wire into a coil
Move the wire faster
What happens when you put a magnet through a coil of wire?
A PD is induced that alternates when the direction of the movement of the magnet changes
Why is work done when you move the magnet in and out of the coil?
When you put the magnet through the coil, the induced current creates its own magnetic field. When the north side goes into the coil, that end of the coil becomes north making it harder to put the magnet in. When you pull the magnet out, that end of the coil turns south attracting the magnet and making it harder to pull out
What type of electricity is created in an alternator?
AC
What type of electricity is created in a dynamo?
DC
At what point in an alternator is the most PD created?
When the coil is horizontal (in line with the direction of the magnetic field) when it is cutting through most of the field lines
At what point is the least amount electricity produced in an alternator?
When the coil is perpendicular to the direction of the magnetic field
Why does an alternator produce AC current?
Because the two sides of the coil are always connected to the same ring, so the polarity of the electricity changes when it cuts through the magnetic field
What is the difference between a dynamo and an alternator?
A dynamo has a split ring commutator (changes contacts every half turn), an alternator has a slip wring commutator so each side of the coil always stays in contact with the same ring
How many peaks are the for a full rotation of a dynamo?
2
What does a complete rotation in an alternator look like on a graph?
The first “N”
