Topic 12 - Magnetism Flashcards
At which part of a magnet are the magnetic forces strongest?
The poles of the magnet.
What happens when two magnets are brought close to each other?
They exert a force on each other
What type of force is exerted if two like poles or magnet are brought near each other?
A repulsive, non-contact force
What type of force is exerted if two unlike poles of a magnet are brought near each other?
An attractive, non-contact force.
What is a magnetic field?
The region surrounding a magnet where another magnet or magnetic material experiences a non-contact force.
What is the difference between a permanent magnet and an induced magnet?
● A permanent magnet produces its own magnetic field
● An induced magnet becomes magnetic when placed in a magnetic field
Induced magnetism always causes what type of force?
A force of attraction.
What is the effect when an induced magnet is removed from a magnetic field?
The induced magnet loses most/all of its magnetism.
Give four examples of magnetic materials.
- Iron 2. Steel 3. Cobalt 4. Nickel
What can always be said about the force between a magnet and a magnetic material?
It is always attractive.
How does the strength of a magnetic field alter as you move further away from the magnet producing it?
The magnetic field strength decreases the further you move away.
In what direction does a magnetic field point?
In the direction of the force that a north pole would experience if placed in the field
● From the north seeking pole to the south seeking pole of a magnet
What does a magnetic compass contain?
A small bar magnet that points in the direction of the Earth’s magnetic field.
What is produced when current flows through a conducting wire?
A magnetic field is produced around the wire.
What determines the strength of the magnetic field around a current-carrying wire?
The magnitude of the current flowing through the wire.
Does a high concentration of field lines mean the field is strong or weak?
Strong
True or false: magnetic field lines never cross each other?
True; they never cross, touch or overlap.
How is a plotting compass used to map out a magnetic field?
● Place a compass (containing a needle magnet) on a piece of paper near the field
● Draw an arrow in the direction the compass points
● Repeat at different points on the paper
● Join the arrows to make a complete field pattern
How does a compass prove earth core is magnetic
- The core is magnetic, and creates a large magnetic field around the Earth
- We know this because a freely suspended magnetic compass will align itself with the earth’s
field lines and point North. - A compass is effectively a suspended Bar Magnet, with its own north pole lining up with Earth’s North Pole
- This cannot be right - like poles repel
- So in fact, Earth’s magnetic pole in the north is a magnetic South Pole and the geographic south pole is close to the magnetic North Pole
Right hand rule
Current produces a magnetic field around a wire
- The direction is dictated by the “right hand rule”
- Plotting compasses on a piece of paper through which a wire is
pierced shows this
- Current direction is perpendicular to the magnetic field
direction
Strength of magnetic field
Magnetic field strength depends on current size; Greater current, stronger magnetic field
- Strength also varies with distance from the conductor; Greater distance from wire, weaker
field
What is a solenoid
A coil of wire which when current passes through creates a strong magnetic field.
Describe the magnetic field found inside a solenoid
Strong and uniform.
Is the field on the outside of a solenoid strong or weak? Why?
Weak.
The fields from each coil cancel out, making the outside field weak.