Magnetism: Magnetic Fields and Properties

Magnetism Basics

• The space around a magnet that exhibits magnetic force is called a magnetic field.
• Magnetic forces operate in a specific area referred to as the magnetic field.
• Magnetic field lines provide information about both the direction and strength of the magnetic field.
• Magnetic field lines travel from the north pole to the south pole.
• The strength of the magnetic field is stronger where magnetic field lines are denser.

Magnetic Properties and Behavior

• Iron filings scattered around a bar magnet cling mainly to its ends.
• The strongest attraction or repulsion in a magnet occurs at its two poles.
• When a compass needle is brought near a bar magnet, it points in the direction of the magnetic field.
• A compass needle aligns with Earth's magnetic field due to the magnetic attraction between the needle and Earth.
• Earth's magnetic north pole is located near the geographic south pole, and Earth's magnetic south pole is located near the geographic north pole.

Declination and Magnetic Fields

• Declination is the angle formed between the direction of a compass needle and the direction of true north.
• The magnetic field of the Earth varies in both magnitude and direction.
• The north magnetic pole of the Earth is located near the Earth's south pole, and the south magnetic pole is located near the Earth's north pole.

Electromagnets and Magnetic Induction

• A magnetic field can be generated around a current-carrying wire.
• Oersted's experiment demonstrated the presence of a magnetic field around a current-carrying wire.
• A magnetic field will be produced by moving electrons.
• Magnetic fields can be created around moving charges.
• A compass needle is deflected when brought near a bar magnet.

Magnetic Poles and Interactions

• Two iron nails touching a magnet will attract each other.
• The magnetic pole at the end of a rubbed magnet can be created by induction.
• The magnetic field around a wire increases when the current in the wire increases and decreases with greater distance.

Solenoids and Magnetic Fields

• The magnetic field is stronger inside a solenoid.
• Increasing current through a wire increases the surrounding magnetic field.
• A current-carrying wire generates a magnetic field.
• The magnetic field generated by current causes a nearby suspended magnet to move.

Lorentz Force

• Factors that increase the Lorentz force: Stronger magnetic field, increased current, and increased length of the wire.
• The direction of the Lorentz force is the result of the interaction between the current direction and the magnetic field direction.