CP10 Flashcards
Why is a bar magnet a permanent magnet?
Because it is always magnetic.
What is a permanent magnet?
A magnet that always stays magnetic.
What is a magnetic field?
The space around a magnet where it can attract magnetic material.
What poles attract to each other when you put two magnets together?
The north pole of one magnet will attract to the south pole of the other magnet and vice versa. Opposites attract.
What is an induced magnet?
A piece of material that becomes a magnet because it is in the magnetic field of another magnet.
How can the shape of a magnetic field be found?
By using plotting compasses.
What is Earths magnetic field similar in shape to?
The shape of the magnetic field of a bar magnet.
What does a current flowing through a wire cause?
A magnetic field.
What does the direction of the magnetic field depend on?
The direction of the magnetic field depends on the direction of the current. If the current changes direction, so does the direction of the magnetic field.
How can you use your thumb to determine the direction of the magnetic field?
If you point your right thumb in the direction of the current, the magnetic field goes in the direction which your fingers are pointing.
What does the strength of the magnetic field depend on?
It depends on the size of the current. The higher the current, the stronger the field.
How does the strength of magnetic field vary by distance?
The magnetic field is strongest closer to the wire and gets weaker with increasing distance.
How does magnetic field around a wire look like?
It looks like multiple circles around the wire.
What is an electromagnet?
A magnet made using a coil of wire with electricity flowing through it.
What is a coil of wire with a current flowing through it?
A coil of wire with a current flowing through it is an electromagnet.
How can the magnetic field of an electromagnet be made stronger?
By putting a piece of iron (an iron core) inside the coil. This iron becomes a temporary magnet - its only magnetic while the field from the electromagnet is affecting it.
What is a ‘motor effect’?
The force experienced by a wire carrying a current that is placed in a magnetic field.
What is the force that a wire experiences near a magnetic field?
This force occurs because the current in the wire creates a magnetic field around the wire and this interacts with the magnetic field between the magnets. The force is experienced as long as the wire is not in the same direction as the magnetic field.
What is Flemings left hand rule?
A way of remembering the direction of the force when a current flows in a magnetic field.
What directions are each fingers in Flemings left hand rule?
- The thumb points up
- The index finger points forward
- The middle finger points right
What do each finger represent in Flemings left hand rule?
- Thumb = Force(F)
- Index Finger = Magnetic field(B)
- Middle Finger = Current(I)
What unit is magnetic flux density measured in?
Newtons per ampere metre(N/Am) but it is also called Tesla(T)
What is the formula for the equation involving ‘force on conductor carrying current at right angles to magnetic field’?
Force(N) = Magnetic flux density(N/Am) x Current(A) x Length(M)
What is the symbol equation for the equation involving ‘force on conductor carrying current at right angles to magnetic field’?
F = B x I x L (F=Force, B=Magnetic flux density, I=Current, L=Length)
