Magnetism and Electromagnetism Concepts

Magnetism

• A force that attracts or repels certain materials, such as iron, and is caused by the movement of electric charges within certain objects, like magnets or electric currents.
• Magnets have two poles, a negative and a positive pole, where the magnetic force is strongest.
• Like charges repel and unlike charges attract
• The region around a magnet that is affected by magnetic forces is called a magnetic field.
• Earth acts as a giant magnet thanks to its magnetic core, which generates a magnetic field that extends far into space.
• Earth’s magnetic field protects us from the solar wind and other harmful particles.
• A compass needle aligns with Earth’s magnetic field because it is a tiny magnet.

Electromagnetism

• Electromagnetic induction is the process of creating an electric current by moving a conductor through a magnetic field or by varying the magnetic field around it.
• Hans Christian Oersted discovered that electric current produces a magnetic field around a wire.
• Electromagnets are produced by wrapping coils of wire around an iron rod.
• The more loops in the coil, the stronger the magnetic field.
• Electromagnets are used in electric motors, loudspeakers, television sets, doorbells, trains, and many other devices.

Electricity

• Electricity is the interaction of electric charges.
• Electric charges are a fundamental property of protons and electrons.
• Protons possess a positive charge, whereas electrons carry a negative charge.
• The electric force is the attraction or repulsion between charged objects.
• Coulomb's Law: The size of charges and the distance between them are key factors in determining the strength of the electric force between charged objects.

Static Electricity

• Static electricity is the build-up of electric charges on an object.
• When you rub a balloon against your hair, electrons from the atoms that make up your hair transfer to the balloon, which makes your hair positively charged due to electron loss.
• The balloon becomes negatively charged due to electron gain.
• Electric discharge is the sudden and brief flow of electrons off of an object.

Electric Current

• Current electricity is a continuous flow of electric charge.
• Current is defined as the quantity of charge that flows past a given point per unit of time.
• The standard unit of measurement for current is the ampere (A).
• Direct current (DC) is a type of electric current where the charges flow in one direction only.
• Alternating current (AC) is a type of electric current that flows in one direction, then the reverse direction, repeatedly.

Conductors and Insulators

• Conductors are materials that allow an electric current to flow through them easily.
• Examples of conductors include metals such as copper, aluminum, silver, and gold, water (when it contains dissolved salts or other charged particles), graphite, and the human body.
• Insulators are materials that resist the flow of electric current.
• Examples of insulators include rubber, air, glass, plastic, wood, and paper.

Electric Circuits

• Electric circuits are closed loops that allow electric current to flow continuously.
• Energy source: An electric field created by a battery's positively and negatively charged terminals attracts and repels charges, providing the push to keep them moving through a closed circuit.
• Load: A component in a circuit that consumes electrical energy to perform a function, such as generating light or motion, and resists the flow of electric current, causing a voltage drop.
• Wires: A low-resistance conductor that carries current in a circuit, connecting components.
• Switch: A switch controls a circuit by connecting or disconnecting two metal pieces.

Test your understanding of magnetism and electromagnetism in this quiz covering key concepts such as magnetic fields, electric charges, and electromagnetic induction. Explore the role of Earth’s magnetic field and its effects on navigation with compasses.