Science Study Guide – Chapter 12
Energy
Heat is the flow of thermal energy.
A campfire has the fastest moving particles.
In order for conduction to occur, two objects must be touching.
Study the diagram below:
Warm water runs over hands
Particles in hands move faster
Hand particles gain energy
A glass baking dish will crack if moved from a very hot oven directly into the
freezer. This is because heat causes matter to expand, and cold causes
matter to contract. When a very hot object like glass is cooled off
too quickly, it contracts fast and cracks.
Humans produce sound when their vocal chords vibrate.
The distance from the top of one sound wave to the top of the next sound
wave is called a wavelength.
The loudness or softness of sound is called volume.
Sonar measures underwater distances by using echoes.
Do you think that sound would travel faster through wood or water? Sound
would travel faster through wood. Sound is created when particles
bump into each other. Since particles in a solid are closer together
than water particles, sound travels faster through wood.
The following statement is NOT true about white light: it contains only
yellow and blue.
Sunburn is caused by ultraviolet light.
A convex lens bends light rays toward the center.
Study the diagram below:
A pencil is placed in a glass of water
Light passes through glass and water
The pencil appears to be broken
How are convex mirrors different from convex lenses? A convex mirror
reflects light and makes things appear smaller. A convex lens does
not reflect light and makes objects appear larger.
The attraction of positive and negative charges is what causes clothes
from a dryer to stick together.
Lightning is a type of static electricity.
A switch in a circuit allows or stops the flow of electricity.
Study the diagram below:
battery
Broken path
Light bulb will not glow
Why do you think electrical wires are covered in rubber or plastic? Rubber
or plastic does not conduct electricity, so when it is wrapped around
wires it keeps people from getting a shock.
A motor is something that changes electrical energy to mechanical
energy.
Aluminum could not be used to power a generator.
A direct current runs in one direction.
Study the diagram below:
Material that
Magnets Attrack
Nickel
Iron
Cobalt
Why do you think a clothes dryer requires a 220 volt outlet while a toaster
only requires a 110 volt outlet? A clothes dryer uses more energy, so it
requires a stronger power source. A toaster does not use as much
energy and can be powered by a 110 volt outlet.