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26 Cards in this Set

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  • Back
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