magnetism/electromagnetism Flashcards
What phenomenon does electromagnetism describe?
Electromagnetism describes the phenomenon whereby electric currents produce their own magnetic fields.
How does an electric current in a wire affect its surrounding magnetic field?
An electric current flowing through a wire produces a magnetic field around the wire.
What is the shape of the magnetic field lines around a straight wire carrying current?
- The magnetic field lines are concentric circles around the wire.
- They are closest together near the wire where the magnetic field is strongest.
What does the direction of the magnetic field depend on?
The direction of the magnetic field depends on the direction of the electric current.
How can you determine the direction of the magnetic field around a wire using your hand?
You can use the right hand rule: point your thumb in the direction of the current and your fingers will curl in the direction of the magnetic field.
What happens to the magnetic field direction when the current direction in a wire is reversed?
The direction of the magnetic field also reverses when the current direction is reversed.
What occurs when two sides of a circular coil interact with each other?
- The concentric circular magnetic fields get stretched out and form ellipses.
- A single magnetic field runs straight through the center of the coil
What is a solenoid?
A solenoid is a long piece of wire wound into a coil with many turns.
How does the magnetic field within a solenoid compare to that of a bar magnet?
The magnetic field within a solenoid is strong and uniform, similar to that of a bar magnet.
What is an electromagnet?
An electromagnet is a magnet created by using electricity to produce a magnetic field.
What happens to an electromagnet when the current is turned off?
The magnetic field disappears when the current is turned off.
How can the direction of the magnetic field in an electromagnet be reversed?
The direction of the magnetic field can be reversed by reversing the direction of the current flow.
What are the four ways to increase the strength of an electromagnet?
- Increase the current flowing through the solenoid.
- Increase the number of turns in the coil while keeping the length the same.
- Decrease the length of the coil while keeping the number of turns the same.
- Add an iron core inside the solenoid.
Why does adding an iron core to a solenoid increase its magnetic field strength?
Iron is a soft magnetic material that becomes an induced magnet when the solenoid is switched on, increasing the magnetic field strength.
What happens to the induced magnetism of the iron core when the current is turned off?
The induced magnetism of the iron core disappears when the current is turned off.
What material was discovered to create the first magnet?
Lodestone or magnetite
What property of lodestone was observed when it was freely suspended?
It settles facing the north-south direction.
What did Hans Christian Oersted discover in 1819?
Electric current can influence compass needles.
What did Michael Faraday discover in 1831?
The motion of a magnet towards or away from a circuit can produce a current.
What are the two main properties of a magnet?
Magnetic pole (polarity) and directional property.
What happens when a bar magnet is dipped into iron filings?
The iron filings cling mainly around the ends of the bar magnet.
What does the observation of iron filings around a bar magnet indicate?
Magnetic attraction is strongest at the ends of the bar magnet.
How can you demonstrate the polarity of a magnet?
By dipping a bar magnet in iron filings and observing where most filings cling.
How can a magnet be used as a compass?
It shows which side is the north pole and which side is the south pole.