Magnetism and Its Uses
Terms
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- Magnetism
- Properties & intereactions of magnets
- Magnetic Force
- Interaction between 2 magnets
- Magnetic Field
- Created by each atom, exerts the magnetic force, surrounds the magnet, & is strongest closest to the magnet
- Magnetic Poles
- Regions of a magnet where the magnetic force exerted by the magnet is strongest
- Magnetic Materials
- Iron, cobalt, nickel
- Magnetic Domains
- Groups of atoms with aligned magnetic poles, like poles point in same direction
- Moving Charges Produce:
- Magnetic fields
- Direction of Field Depends on:
- Direction of the current
- Strength of Magnetic Fields Depends on:
- Amount of current flowing in the wire
- Electromagnet
- Temporary magnet made by placing a piece of iron inside a currnet-carrying coil of wire, Converts electrical energy into mechanical energy to do work
- Increase Strength of Magnetic Fields by:
- Adding turns to wire coil or increasing current
- Galvanometer
- Device that uses an electromagnet to measure current
- Electric Motor
- Device that changes electrical energy into mechanical energy, Connected to voltage source
- How Electric Motor Works
- Electromagnet is free to rotate between poles of permanent, fixed magnet. Magnetic field produced in coil from current. Direction changes of current cause coil to rotate.
- How Rotation Speed of Electric Motors Controlled
- Vary amount of current flowing through coil, More current = stronger magnetic field & coil turns faster
- Electromagnetic Induction
- Production of electric current by moving a loop of wire through a magnetic field/moving a magnet through a wire loop
- Generator
- Device that produces electric current by rotating a wire coil in magnetic field
- How Generator Works
- Wire coil wrapped around iron core is placed between poles of a permanent magnet. Coil is rotated by mechanical energy and electric current flows through coil. Direction of current in coil changes twice w/ each revolution.
- Direct Current (DC)
- Current that flows in 1 direction through wire
- Alternating Current (AC)
- Reverses direction of the current flow in regular way (In USA, generators produce a frequency 60 cycles per second/60Hz)
- Transformer
- Device that increases or decreases the voltage of alternating current, Made of 2 coils (primary & secondary) wrapped around same iron core
- Step-up Transformer
- Increases voltage, Secondary coil has more turns of wire than primary coil does
- Step-down Transformer
- Reduced voltage, Secondary coil has fewer turns of wire than primary
- Commutator
- Reversing switch in a motor that rotates w/ an electromagnet
- Ammeters
- Measure the electrical current passing through a circuit
- Brushes
- Electrical outlets in a motor that transferss energy from the motor to the commutator