Magnetism and Electromagnetism Flashcards
Name the two poles of a magnet.
North (-seeking) and south (-seeking) poles.
What is a magnetic field?
A region in which there is a force on a magnet or magnetic material.
In which direction do field lines always point?
From the north pole to the south pole.
Name two magnetic poles that will attract each other.
North and a south.
Name two magnetic poles that will repel each other.
North and a north, or south and a south.
State two ways you can find out the shape of a magnetic field.
Iron filings, plotting compasses
State the type of material you can use for the core of an electromagnet.
Soft iron core
State three factors that affect the strength of an electromagnet.
Number of turns on the coil, the size of the current and the type of core.
State a use of electromagnets.
Loudspeaker, electric bell, circuit breaker.
Explain why the needle of a compass always points in the same direction wherever you point it in a room.
A compass needle always points in a north–south direction. The compass needle lines up in the Earth’s magnetic field.
Define the term solenoid.
A wire wound into a coil.
What is an electromagnet.
A non-permanent magnet turned on and off by controlling the current through it.
What is a magnetic field line?
An imaginary line that shows the direction of the force on a magnetic material.
How can magnetic field lines show the strength of a magnetic field?
The closer the field lines are together, the stronger the magnetic field at that point.
Define the term ‘permanent magnet’.
An object that is magnetic all of the time.
Explain the difference between a permanent magnet and a magnetic material.
A permanent magnet has its own magnetic field, a magnetic material will experience a force if it is placed in a magnetic field.
State two advantages of electromagnets over permanent magnets.
You can turn electromagnets on and off; you can vary the strength of electromagnets and make much stronger electromagnets than permanent magnets.
Explain why iron is used as the core of electromagnet rather than steel.
Iron is easy to magnetise and demagnetise. Steel does not lose its magnetism easily; if you turned the electromagnet off, the steel would still be magnetic.
Complete the sentence: When a _____ flows in a wire it produces a magnetic field around it.
current
Describe how to make an electromagnet.
Wind a coil of wire around a soft iron core and pass a current through it.
