Physics 6 - Magnetism and electromagnetism Flashcards
6.2 Describe the force between magnets and magnetic substances
Magnets attract magnetic substances
6.3 Describe the properties of magnetically hard and soft materials
Magnetically soft materials lose their magnetism quickly
Magnetically hard materials keep their magnetism permanently
6.3 Give the uses of a magnetically hard and magneticallysoft materials
Soft - electromagnets as they can change their magnetic field quickly
Hard - permanent magnets
6.4 Define magnetic field and magnetic field lines
Magnetic field - region where magnetic fields feel a force
Field lines - show the size (density of the field lines) and direction (arrows on field lines pointing from North to South)
6.5 Sketch the magnetic field between two like poles
JFDI - See Onenote
6.5 Sketch the magnetic field between two unlike poles
JFDI - See Onenote
6.5 State the elements and compounds where magnetism can be induced and describe how
Induced in iron, cobalt, nickel and steel when they are placed in a magnetic field (domains aligning)
6.6 practical: Design an experiment to investigate the magnetic field pattern for a permanent bar magnet
Place the magnet on a flat surface
Place a sheet of paper on top and then sprinkle on iron filings
Shake the paper until they align in field lines
Use a plotting compass to determine the direction of the field line
OR use plotting compasses and draw a line between them
6.7 describe how to use two permanent magnets to produce a uniform magnetic field pattern
Place two unlike poles with magnetic fields of similar magnitudes opposite each other.
There is a uniform magnetic field between the two poles
6.8 How can a conductor produce a magnetic field?
Pass a current through it
6.9P Describe the construction of electromagnets
Wrap an insulated wire around a soft iron nail.
Connect the wires to a power supply. The current though the wires creates an electromagnet
6.10P draw magnetic field patterns for the following when each is carrying a current:
a straight wire
JFDI - See one note
If the wire is pointing upwards, the magnetic field is in a circle around it. The field lines get closer together the more central it is
6.10P draw magnetic field patterns for the following when each is carrying a current:
a flat circular coil
JFDI - See Onenote
Each of the two wires has a circle of magnetic field lines around it. In the middle, there is one straight line
6.10P draw magnetic field patterns for the following when each is carrying a current:
a solenoid
Field lines travel through the coil from N to S and some go around it
6.11P Describe the force on a charged particle in a magnetic field
There is a force on a charged particle when it moves in a magnetic field (provided its motion isn’t parallel to the field).
The force is perpendicular to the direction of motion and the direction of the magnetic field.
6.12 Explain why a force is exerted on a current-carrying wire in a magnetic field
The magnetic field of the wire interacts with the external magnetic field creating a force
6.12 Describe how a d.c. electric motor works
A current is passed through the coil - the magnetic field of that interacts with the external one creating a force - that spins the coil.
Every half turn the split-ring commutator changes the direction of the current around the loop so that it spins in one direction.
6.12 Describe how a loudspeaker works
A coil is placed on a permanent magnet, and is wrapped around the base of the cone. An a.c. current is passed through it.
The magnetic field of the coil by the a.c. current interacts with the permanent magnet’s magnetic field creating an alternating force.
The cone vibrates backwards and forwards, creating sound.
6.13 A wire carries a current perpendicular to a magnetic field. Describe how to determine the direction of the force on the wire
Use the left hand rule:
First finger - magnetic field (North to South)
Second finger - current (conventional current)
Thumb - motion/thrust (direction of the force)
6.14 Describe factors that increase the force on a current-carrying conductor in a magnetic field, such as the coil in a motor or speaker
More current
More turns on the coil
Stronger magnetic field
Soft iron core in the coil
6.14 Describe how the direction of the force on a current-carrying conductor in a magnetic field can be changed
Change the direction of the current or the poles of the magnet
