magnetism Flashcards
(44 cards)
What is electromagnetic induction?
Electromagnetic induction is when a voltage is induced in a conductor or a coil when it moves through a magnetic field or when a magnetic field changes through it.
What is the generator effect?
The generator effect refers to the induction of current in a conductor when it moves through a magnetic field, without any initial current present.
What is the motor effect?
The motor effect occurs when there is already a current in the conductor which experiences a force in a magnetic field.
What induces a potential difference in a conductor?
A potential difference is induced in a conductor if there is relative movement between the conductor and the magnetic field.
How can a potential difference be induced in a wire?
By moving the wire through a magnetic field, cutting through the field lines.
What happens when a magnet moves through a coil?
The field lines cut through the turns on the coil, inducing a potential difference in the coil.
Which instrument can measure the induced potential difference?
A sensitive voltmeter.
What factors affect the induced potential difference?
The size of the induced potential difference is determined by:
* The speed of movement
* The number of turns on the coils
* The size of the coils
* The strength of the magnetic field
How does increasing the speed of the conductor affect the induced potential difference?
Increasing the speed will increase the rate at which the magnetic field lines are cut, thus increasing the induced potential difference.
What is the effect of increasing the number of turns on the coils?
Increasing the number of turns will increase the potential difference induced.
What happens if the length of wire is reduced while maintaining the number of turns?
The potential difference induced will increase because each coil will cut through the magnetic field lines.
How does the size of the coils affect the induced potential difference?
Increasing the area of the coils will increase the potential difference induced.
What is the relationship between the strength of the magnetic field and the induced potential difference?
Increasing the strength of the magnetic field will increase the potential difference induced.
How does the orientation of the poles of the magnet affect the induced potential difference?
Reversing the direction in which the wire, coil, or magnet is moved will change the direction of the induced potential difference.
What is an alternator?
An alternator is a type of generator that converts mechanical energy to electrical energy in the form of alternating current.
What is the main component of a simple alternator?
A rotating coil in a magnetic field with slip rings.
What happens when the coil in an alternator turns?
The pointer deflects first one way, then the opposite way, and then back again due to the alternating potential difference induced.
How is alternating current produced in an alternator?
By the coil cutting through the magnetic field lines or when a magnet rotates within a stationary coil.
What is a dynamo?
A dynamo is a direct current generator that also uses a rotating coil in a magnetic field.
What distinguishes a dynamo from an alternator?
A dynamo has a split-ring commutator instead of two separate slip rings.
What does the split-ring commutator do in a dynamo?
It changes the connections between the coil and the brushes every half turn to keep the current in the same direction.
What is the output current type from a dynamo?
The output current from a dynamo is direct current (D.C.).
True or False: Motors and generators perform the same function.
False.
Fill in the blank: The key principle for generating alternating current is the ______ between the coil and the magnet.
[relative motion]
