Chapter 5.4 and 5.5

Question 1

Thermal Equilibrium

Answer 1

When heating is balanced by cooling.

Question 2

Temperature

Answer 2

A measure of how energetically the atoms that make up an object are moving about.

Question 3

Thermal Motions

Answer 3

The random motion of atoms and molecules that create temperature.

Question 4

Absolute Zero

Answer 4

The temperature at which all thermal motions stop.

Question 5

Kelvin Temperature Scale.

Answer 5

Starts with absolute 0 at 0. Same degrees at Celsius add 273.15. So water freezes at 27.15 and boils at 373.15K

Question 6

Why is Kelvin useful?

Answer 6

When temperature is measured in kelvin, the energy of the particles is proportional to the measured temperature. So, 200k is twice as energetic as 100k.

Question 7

Luminosity

Answer 7

The total amount of light leaving a source. Measured in watts.

Question 8

Luminosity

Answer 8

The total amount of light leaving a source. Measured in watts.

Question 9

Blackbodies

Answer 9

Objects that emit electromagnetic radiation only because of their temperature, not their composition. Emit just as much radiation as their absorb through their surroundings

Question 10

Blackbody Spectra

Answer 10

The spectrum of electromagnetic energy emitted by a blackbody per unit of area per second.

Question 11

Stean Boltzmann Law

Answer 11

The increase of the luminosity of a blackbody is proportional to the fourth power of the temperature. F=ot^5

Question 12

Flux

Answer 12

Amount of energy radiated by each square meter of the surface of an object each second.

Question 13

Luminosity= (flux) * _____

Answer 13

Surface area of the object.

Question 14

F=oT^4

Answer 14

Stefan Bolzman law. Flux is equal to sigma times the temperature to the fourth power.

Question 15

If the temperature of an object doubles what happens to the amount of energy being released?

Answer 15

It goes up by 2^4 or 16 times the original energy.

Question 16

Wien’s Law

Answer 16

The wavelength of the spectrum is inversely related to th temperature of the object. If you double the temperature, the peak wavelength becomes half of what it was. T= b/peak wavelength

Question 17

Stefan Boltzmann Constant

Answer 17

5.67 times 10^08 watts/m2k^4

Question 18

Brightness

Answer 18

The amount of light arriving at a particular location.

Question 19

Brightness vs Luminsoity

Answer 19

Brightness depends on distance because it measure slight arriving at a location. Luminosity is independent because it measures light leaving an object.

Question 20

How does brightness depend of distance.

Answer 20

Is is inversely proportional to the square of the distance between the source and the object.

Question 21

Brightness=

Answer 21

Luminsoity/4pied^d2

Question 22

Albedo

Answer 22

Fraction of light that reflects from a planets surface

Question 23

A planet covered in snow would have close to a ___ albedo. A planed covered in black rocks would have close to ___ albedo

Answer 23

1, 0