Magnetism and electromagnetism pt2 Flashcards
How can the potential difference be induced?
- an electric conductor moving relative to a magnetic field
- a change in the magnetic field
A potential difference is induced across _____________
the ends of the conductor
What is the generator effect?
if the conductor is part of a complete circuit, a current is induced in the conductor
What does an induced current generate?
a magnetic field that opposes the original change* which produces it.
- the movement of the conductor, or the change in the magnetic field
How do you increase the size of induced potential difference?
- increase the speed of the movement
- size of the magnetic field
- shape wire into a coil: greater number of coils
What reverses the direction of any induced current?
reversing the direction of the movement or magnetic field
What happens in an alternator?
- a rotating coil is used in a magnetic field
- this allows for the kinetic energy of a rotating coil to be converted to the electrical energy of an induced electric current
- As the magnet rotates, the direction of the field through which the coil passes alternates: it cuts through the field lines
- this induces an alternating potential and an alternating current
How can the induced p.d and current in an alternator be increased?
- rotating the coil more quickly
- increasing the magnetic field strength
- increasing the number of turns on the coil
- increasing the area of the coil
For alternator, the speed of rotation is _________
the frequency of the alternating current
How is current able to pass out of the coil in alternators?
the coil is connected to 2 commutators
When is maximum and minimum p.d created in alternators and dynamos?
- why is this
A p.d s induced when the wire passes a magnetic field
Maximum p.d is achieved when the alternator is horizontal because at this point the wire is sweeping directly through the magnetic field lines at the fastest possible rate
Minimum p.d is created when the coil is vertical = 0 p.d = because the coil is moving parallel to the field line, so it’s not cutting through magnetic field lines
why are there negative values for p.d in alternators?
As the coil continues moving around we get a maximum p.d again but in the opposite direction = because the 2 sides of the coil are now moving in a different direction than before
P.d values in alternators change from + to -.
What does this mean?
that it produces alternating current
Explain why alternators produce alternating CURRENT
not p.d!!!
When the given side of the coil is moving upwards than the magnetic field, the current will flow through it in one direction.
when the same side move down, the current will flow through it in the opposite direction
How do you plot a magnetic field around a magnet?
1) place the plotting compass near the magnet on a piece of paper
2) mark the direction the compass needle points
3) move the plotting compass to many different positions in the magnetic field, marking the needle direction each time
4) join the points to show the field lines