Magnetism Flashcards
(30 cards)
What is a magnetic field?
The region around a magnet where magnetic forces can act on another magnet or magnetic material.
What is a magnet?
Any material or object that produces a magnetic field
What are the only materials that can be magnetised and why ? (Ferromagnets)
Only, Iron, steel, cobalt, and nickel because they are ferromagnetic—they have domains that can be aligned by a magnetic field.
How can you show the shape of a magnetic field?
Using iron filings or a plotting compass.
What is the direction of a magnetic field line?
They point from the north pole to the south pole of a magnet and indicate the strength of the field
What happens when you bring like poles of magnets together?
They repel each other
What happens when you bring unlike poles of magnets together?
They attract each other
Explain the difference between permanent magnets and induced magnets.
Permanent magnets produce their own magnetic field. Induced magnets become magnetic only when placed in a magnetic field and lose magnetism when removed.
How do you increase the strength of an electromagnet?
Increase the current, increase the number of coils, or use a soft iron core.
What is the magnetic field around a straight wire carrying current?
A series of concentric circles centered on the wire.
What rule is used to find the direction of the magnetic field around a current-carrying wire?
The right-hand thumb rule
What is the motor effect?
A current-carrying wire in a magnetic field experiences a force.
What does the size of the force in the motor effect depend on?
The current, the strength of the magnetic field, and the angle between them.
What is Fleming’s Left Hand Rule used for?
To determine the direction of force in the motor effect.
State the equation for the force on a current-carrying wire in a magnetic field.
F = B × I × L
(Force (N) = Magnetic flux density (T) × Current (A) × Length of wire in field (M) )
How can you make a temporary magnet?
Stroke a ferromagnetic material (like iron) with a permanent magnet to align its domains
Why is soft iron used in the core of electromagnets?
It magnetises and demagnetises quickly, making the electromagnet switch on and off easily.
Describe how to plot the magnetic field around a bar magnet.
Place a magnet on paper and use a plotting compass to trace the direction of field lines, starting at the north pole and drawing arrows toward the south pole.
In a bar magnet diagram, where is the field strongest?
At the poles, because the field lines are closest together there.
How do you draw magnetic field lines around a bar magnet?
Draw smooth curved lines from the north to the south pole.
The lines must never cross.
Use at least 5 lines, symmetrical.
Include arrows to show direction.
What is a ferromagnetic material?
A material that can be magnetised because its magnetic domains can align in the same direction when placed in a magnetic field.
What is a ferromagnetic material?
Because it contains iron, which is a ferromagnetic material.
What happens to the magnetic domains in a ferromagnetic material when it is magnetised?
The domains align in the same direction, producing a strong overall magnetic field.
