Section 3.2

Question 1

True or false

Light is a wave, not a particle

Answer 1

False, light has both wave like properties and particle properties

Question 2

What is the fundamental unit of light?

Answer 2

Photon

Question 3

True or false

Photons have mass

Answer 3

False

Question 4

True or false

Photons travel at the speed of light through the vacuum of space

Answer 4

True

Question 5

Electric and magnetic fields lay ______ to each other

Answer 5

Perpendicular

Question 6

Identify the variables:

c = lamda / v

Answer 6

C = speed of light (constant)
V = frequency
Lamda = wavelength

Question 7

Short wavelengths have _______ frequency

Answer 7

High

Question 8

In terms of waves what is a crest?

Answer 8

The peak of a wave

Question 9

In terms of a wave what is the trough?

Answer 9

The low point of a wave

Question 10

In terms of a wave what is amplitude?

Answer 10

The distance from the centre line to the crest or trough.

Question 11

In terms of a wave what is the wavelength?

Answer 11

The distance between two crests

Question 12

In terms of a wave what is the period?

Answer 12

The time it takes a wave to pas a stationary point.

Question 13

In terms of a wave what is frequency?

Answer 13

The amount of waves that pass a stationary point in a set period of time

Question 14

Microwaves have wavelengths of …..

Answer 14

0.1 to 100 cm

Question 15

Radio wavelengths are ….

Answer 15

100cm +

Question 16

Gamma rays and x-rays are ______ frequency

Answer 16

High

Question 17

Wavelengths lower than 0.4 mm are …..

Answer 17

UV rays

Question 18

Visible light is approximately from _____ to ______ micrometers in wavelength

Answer 18

0.4, 0.7

Question 19

The earth emits ________ radiation.

Answer 19

Infrared

Question 20

Define a blackbody.

Answer 20

An object that absorbs all incoming radiation and emits all energy at full efficiency in all wavelengths

Question 21

True or false

Objects above absolute zero emit electromagnetic radiation.

Answer 21

True

Question 22

Most examples of blackbody objects are a _______ source

Answer 22

Thermal

Question 23

The source of earths electromagnetic radiation is the…..

Answer 23

Sun

Question 24

True or false

A television, lightning and fluorescent light are all examples of blackbody radiation.

Answer 24

False

Question 25

Give two examples of blackbody radiation.

Answer 25

Burner on electric stove | Incandescent light bulb

Question 26

What scientist is related to blackbody radiation?

Answer 26

Max Planck

Question 27

What is Wien displacement law?

Answer 27

The wavelength that yields the most radiation can be calculated for a given temperature

Question 28

The solar peak of radiation is in the ________ wavelengths

Answer 28

Visible

Question 29

Define irradiance.

Answer 29

The radiant flux that is incident on a surface

Question 30

Define radiance.

Answer 30

The total amount of energy measured by a sensor in a given direction representing a grounded point

Question 31

Define reflectance.

Answer 31

The true image a sensor picks up, taking a radiant image and removing interferences like atmospheric scattering

Question 32

What is transmittance in the atmosphere?

Answer 32

Some radiation penetrates a specific surface of a specific material and slows down.... Bending light

Question 33

What is atmospheric absorption?

Answer 33

Particles absorb radiation and could possibly re-emit it in a longer wavelength.

Question 34

What is atmospheric reflection and scattering?

Answer 34

Surface angle and texture determines if radiation is reflected 180 deg or scattered in numerous directions

Question 35

All forms of remote sensing rely on part of the ....

Answer 35

Electromagnetic spectrum

Question 36

What are the three types of atmospheric scattering?

Answer 36

Rayleigh Mie Non selective

Question 37

Define Rayleigh scattering.

Answer 37

Scattering which occurs when the size of the particles is smaller than the wavelength of light.

Question 38

Define Mie scattering.

Answer 38

It is another term for non molecular scattering. It is when there is sufficient quantity of materials with diameters 0.1 to 10 times the wavelength of light

Question 39

What is non selective scattering?

Answer 39

It is the most problematic of the atmospheric scattering and only occurs in the lower portion of the atmosphere

Question 40

What type of scattering accounts for blue light in the sky?

Answer 40

Rayleigh scattering

Question 41

What accounts for the red light in the sky?

Answer 41

Rayleigh and Mie scattering

Question 42

What are the most common effects of non selective scattering?

Answer 42

Fog and cloud

Question 43

Scattering leads to ______ in an image.

Answer 43

Path radiance

Question 44

What does path radiance add to an image?

Answer 44

Noise and a washed out image

Question 45

What happens when the AFOV is larger than the depth of the atmospheric column?

Answer 45

Lots of noise is generated at the edges of the image

Question 46

Define reflection.

Answer 46

The process where energy interacts with an object and bounces back off an object

Question 47

What are the two types of reflection?

Answer 47

Diffuse (lambertian) | Specular

Question 48

Define reflectance.

Answer 48

The fraction of incident energy that is reflected by a surface that is quantifiable

Question 49

What is the difference between reflectance and reflection.

Answer 49

Reflection is the process and reflectance is the fraction measure that is comparable

Question 50

What is a diffuse (lambertian) reflector?

Answer 50

Rough surfaces that reflect uniformly in all directions.

Question 51

What is a specular reflector?

Answer 51

A mirror like surface where the angle of reflection is equal to the angle of incidence

Question 52

What is the term to describe a surface that is both specular and diffuse?

Answer 52

Bidirectional reflectance

Question 53

Name five things that could influence the signal from a bidirectional reflector.

Answer 53

``` Illumination Sensor Vegetation Understory Soil ```

Question 54

Define refraction.

Answer 54

The bending of light that occurs as light goes through a material. This happens because the speed of light changes

Question 55

Most remote sensing systems collect _______.

Answer 55

Reflected radiation

Question 56

What is a spectral signature?

Answer 56

The amount of solar radiation transmitted in a wavelength. These help us identify materials. This can also be called a spectral curve

Question 57

What is a feature space?

Answer 57

Using two or more wavelengths and the spectral signature is plotted in a multidimensional space

Question 58

How does the amount of rejected energy distinguish between surfaces?

Answer 58

Different surfaces absorb and reflect different wavelengths and looking at the spectral signature can help distinguish these