Magnetism Basics Quiz

Magnetism Basics

• Origin of "Magnet": The word "magnet" originates from the ancient region of Magnesia (now part of Turkey).
• Lodestone: Large numbers of black stones were found in the region that could attract iron. These stones were called lodestones or leading stones because they could be used for navigation and eventually for making compasses.
• Magnetite: The mineral form of these stones is magnetite.
• Magnetic Field: The region around a magnet where magnetic force acts on magnetic materials.
• Showing Magnetic Field: Iron filings sprinkled on a piece of card laid over a magnet line up to show the magnetic field pattern, particularly the lines of force that arch between the poles.

Magnetic Field Strength

• Distance and Strength: The distance between lines of force in the magnetic field can indicate strength. The closer the lines, the stronger the field.

Interaction of Magnetic Fields

• Similar Poles: If two similar magnetic poles are brought together, a specific pattern of interaction develops between them.
• Opposing Poles: If two opposing magnetic poles are brought together, the pattern of interaction will differ from that of similar poles.
• Magnetic Field Patterns Change: The magnetic field pattern of one magnet changes when another magnet is brought nearby.

The Earth's Magnetic Field

• Inner and Outer Core: The core of the Earth is comprised of an inner core made of solid iron and nickel and an outer core made of liquid iron and nickel. They move at different speeds, which creates the Earth's magnetic field.
• Earth's Magnetic Axis: The magnetic axis of the Earth is slightly offset from its geographic axis.
• Geographic vs Magnetic Poles: The geographic poles (fixed locations) are different from the magnetic poles (which change position slightly each year).

Early Discoveries of Magnetism

• Ancient Chinese (Luopan): Ancient Chinese civilization likely pioneered the use of magnets for navigation. A compass-like device called a luopan was used, utilizing south-pointing magnetic direction to assist in architecture.
• Shen Kuo: The first evidence of scientific investigation into magnetism is found in the written works of Chinese scientist Shen Kuo.
• Petrus Peregrinus / Peter the Pilgrim: A 13th-century French engineer experimented on magnets and magnets' attractive and repulsive properties.
• William Gilbert: An English scientist from the 16th/17th century who accurately described the Earth as a giant magnet.

Magnetism and Electricity

• Hans Christian Ørsted: He noticed a connection between electricity and magnetism: a compass needle moved when an electric current flowed nearby.
• Electric Current and Magnetic Field: An electric current passing through a wire creates a magnetic field around the wire. The strength of the field varies at different locations.
• Plotting a Magnetic Field: The pattern of the field can be plotted using compasses and iron filings.
• Electromagnets: A coil of wire surrounding a piece of iron can create an electromagnet. Current through the coil induces magnetism in the iron, and the field disappears when current stops.
• Electromagnet Applications: Electromagnets are used in a variety of devices, such as scrapyards (moving cars and steel).

Making and Testing Electromagnets

• Materials: A nail, copper wire, switch, batteries, clamp and stand, and paper clips.
• Creating Electromagnet: Wind the copper wire around the iron core, ensuring tight turns in the same direction.
• Testing Electromagnet: Set up circuits using differing cell configurations and observe how an electromagnet's strength (measured by the number of paper clips lifted) changes based on the number of cells. This experiment would vary the strength of the electromagnet based on the amount of electricity flowing through the coil.