Physics Ch.22 Study Guide

Good emitters of radiant energy are also good ______________

absorbers

An object in thermal equilibrium is both ________and________ energy at the same rate

absorbing; radiating

examples conductors

aluminum; silver; iron; copper

Objects of everyday temperatures emit waves mostly in the ______ ________end of the infrared region.

long-wavelength

Do objects at low temperatures emit waves with a longer or shorter wavelength than objects with higher temperatures?

longer

_______ are the best conductors

metals

The rate of cooling of an object is approximately proportional to the temperature difference between the object and its surroundings

newton's law of cooling

Order the different types of radiant energy from longest to shortest wavelength by placing a number from 1 to 7 beside each.

radio waves; microwaves; infrared radiation; visible light; ultroviolet light; x-rays; gamma rays

is the main greenhouse gas.

water vapor

Convection currents stirring the atmosphere produce________

winds

examples insulators

wood; straw; air; cork; woll; papper; polystyrene

What is a conductor?

A conductor is a material that conducts heat well.

Why can't energy move from the sun to Earth by conduction or convection

Conduction is the transfer of heat from molecule to molecule, and convection is the transfer of heat by expansion and rising of matter. Both of these are impossible in space because there is almost no matter.

. Use the figure above to explain Earth's global warming

Earth's atmosphere allows short waves from the sun to pass through. These waves strike Earth, which re-radiates the energy as longer waves. Atmospheric gases absorb and re-emit much of this long-wavelength radiation back to Earth.

You notice that a blacktop pavement becomes hotter than other nearby surfaces on a hot day. What will you notice about the temperature of the blacktop pavement at night?

It will cool faster than other surfaces

Suppose you have a box, painted white inside, which is closed except for a hole 2 centimeters wide. Circle the letter beside the sentence that explains why the hole appears black.

Light that enters is reflected and partly absorbed so many times that little is left to come out.

Imagine stepping with one bare foot onto metal and with the other bare foot onto wood. Explain why the metal feels cool and the wood feels warm, even though they have the same temperature

Metal is a good conductor, but wood is a poor conductor. Heat easily moves out of your foot into the cooler metal. Little heat moves out of your foot into the wood, so your foot does not sense that it is touching something cooler.

Explain why the inside of a car becomes so much hotter than its surroundings on a hot day.

Short wavelengths from the sun can pass through the car's glass and into the car, warming the car. The car radiates longer wavelengths that cannot pass out through the glass. The energy is trapped inside the car.

Explain why snow is sometimes used to construct dwellings in cold climates

Snowflakes imprison a lot of air in their crystals and are good insulators. The snow prevents heat from escaping too rapidly

Suppose a heater is placed near the floor of a room. Describe the steps in which convection currents keep the air stirred up in the room

The heater warms nearby air, and the warm air rises. Cooler air near the ceiling moves downward, and the heater warms it. This air then rises, and the process continues.

The figure above shows ice at the bottom of a test tube and boiling water at the top. Explain why the heat that boils the water doesn't melt the ice.

The hot water at the top of the tube is less dense and floats. Any heat that reaches the ice must be transferred by conduction, but water is a poor conductor of heat.

Explain the two ways convection currents produced by uneven heating of Earth's surface produce sea breezes. a. During the day: b. At night:

The shore warms more easily than the water. Air over the shore rises, and cooler air from above the water takes its place, producing a breeze toward the land. The shore cools off more quickly than the water. Air over the water rises, and cooler air from above the shore takes it place, producing a breeze toward the sea.

On a sunny day, Earth's surface is a net _______ , and at night it is a net____________-

absorber; cooler

the warming of a planet's surface due to the trapping of radiation by the planet's atmosphere

greenhouse effect

How do birds vary their insulation?

by fluffing their feathers to create air spaces

Air is transparent to both infrared (long) waves and visible (short) waves, unless the air contains excess _________and________

carbon dioxide; water vapor

Record-breaking cold nights occur when the skies are _______________

clear

is the gas most rapidly increasing in the atmosphere.

co2 (carbon dioxide)

. In conduction, ________between particles transfer thermal energy.

collisions

When a molecule collides with a molecule that is receding, its rebound speed after the collision is ________than it was before the collision.

less

the transfer of energy within materials and between different materials that are in direct contact

conduction

An object hotter than its surroundings eventually ______________ to match the surrounding temperature.

cools

A good absorber of radiant energy appears ______________

dark

In expanding air, the average speed of the molecules ________, and the air cools.

decrases

Radiation is energy transmitted by ___________ ___________

electromagnetic waves

. Define radiant energy.

energy that is transmitted by radiation

. Is the following sentence true or false? All substances continuously emit only one specific wavelength of radiant energy

false

Is the following sentence true or false? All substances continuously emit only one specific wavelength of radiant energy

false

Is the following sentence true or false? As air rises, it expands because more atmospheric pressure squeezes on it at higher altitudes

false

Is the following sentence true or false? Both heat and cold are forms of energy.

false

Is the following sentence true or false? Materials that are good conductors of heat are usually poor conductors of electricity.

false

The average _____________of radiant energy is directly proportional to the Kelvin temperature of the emitter

frequency

In convection, heat is transferred by movement of the________ substance from one place to another

hotter

Circle the letter of the type of radiant energy you feel as heat if you sit near a fireplace

infrared radiation

any material that is a poor conductor of heat and that delays the transfer of heat

insulator

The part of radiant energy that is absorbed by objects increases the ________ energy of the objects.

internal

Is the following sentence true or false? Newton's law of cooling also holds for heating.

true

. Order the star colors white, red, and blue from coolest to hottest.

red, white, blue

The radiant energy emitted by stars is called

stellar radiation

An infrared thermometer measures the infrared radiant energy emitted by a body and converts it to _______________.

temperature

The __________of an object doesn't change if it is in thermal equilibrium.

temperature

The radiant energy emitted by Earth is called

terrestrial radiation

A hot apple pie will cool faster in a freezer than on a kitchen table because

the temperature difference is greater.

Glass is to ____________visible light waves, but _____________-- infrared waves

transparent; absorbs

Is the following sentence true or false? An insulator cannot totally prevent heat from getting through, but instead just reduces the rate at which heat penetrates.

true

Is the following sentence true or false? As air rises and expands, it collides with more molecules that are receding than are approaching.

true

Is the following sentence true or false? Conduction occurs without any overall transfer of matter

true

Is the following sentence true or false? Light-colored objects reflect more light than dark-colored ones

true