Magnetism Flashcards
What happens when current flows through a wire?
A magnetic field is formed around the wire
What is the rule for current flowing through a wire?
RIGHT HAND RULE,
The thumb is the direction of current and the fingers wrapped around the thumb is the direction of the magnetic field.
The closer to the wire, the stronger the magnetic field.
What is the magnetic field around a wire made of?
Concentric circles
Does the magnetic field around a wire have poles?
No
How to increase the magnetic field around a wire?
Increasing the current flowing though the wire
What happens to the magnetic field when a wire is looped?
When a wire is looped into a coil, the magnetic field lines circle around each part of the coil into the centre of the coil
How to increase the magnetism around a wire?
Increasing the amount of coils to form a solenoid
Properties of a solenoid
The magnetic field inside the solenoid is strong and uniform
One end of the solenoid behaves like a south pole and the other end behaves like a north pole.
If the current changes direction, the north pole and south pole will switch
What does it mean if there is no magnetic field around a wire?
There is no current
How to increase the magnetic field around a solenoid?
Increasing the size of the current
Increasing the amount of coils
Adding an iron core
What will the iron become when wrapped inside a solenoid?
An induced magnet
What is an electromagnet?
A solenoid with an iron core
The magnetic field produced from the magnet can be turned on and off by turning the current on and off
Examples of electromagnets
A scrap yard crane.
An electric bell (explanation on flashcard)
What is the motor effect?
Occurs when a wire with current flowing through it is placed in a magnetic field such as in between two magnets
This makes the wire experience a force
Factors affecting the force in the motor effect
- Using stronger magnets
- Increasing the current
- Placing the wire 90 degrees to the direction of the magnetic field lines between the poles of the magnet (RESULTS IN MAXIMUM INTERACTION)
What happens if two magnetic fields are parrallel in the motor effect?
There will be no interaction so no force
What is flemmings left hand rule?
The direction of the force (aka thrust) on a current carrying wire depends on the directions of the magnetic fields.
ALL 3 ARE PERPENDICULAR TO EACHOTHER
What do the fingers represent in flemmings lefthand rule?
Thumb is for Thrust aka force
First finger is for field
Second finger is for the current
How do Electric motors work?
The motor effect can create a simple D.C electric motor
Explanation of flash card
How do headphones and loudspeakers work?
They convert electrical signals into sound using the motor effect
( EXPLANATION ON FLASHCARD)
What is the difference between the generator effect and the motor effect?
The wire or circuit in the motor effect has current passing though it, so two magnetic fields are interacting with eachother creating a force.
The wire or circuit in the generator effect has no current passing though it, instead the magnetism between the magnets create a potential difference in the wire when in contact. When you take the wire or circuit into and away and into again the magnetic field between magnets the direction of the potential difference changes.
What factors affect the generator effect?
The speed at which the coil, magnet or wire is moved
The number of coils
The size of the coils
The strength of the magnetic field
What is Lenz law
The direction of an induced potential difference always opposes the change that produces it
This means that any magnetic field created by the potential difference will act so that it tries to stop the wire or magnet from moving
What can the generator effect be used to do?
To create and AC (In an alternator) or DC (In a dynamo)
What does an alternato do?
A simple alternator is a type of generator that converts mechanical energy to electrical energy in the form of alternating current
What does a dynamo do?
A dynamo is a direct-current generator
A simple dynamo is the same as an alternator except that the dynamo has a split-ring commutator instead of two separate slip rings
