Lesson 5

Question 1

Why is light a form of energy? What type of energy is it?

Answer 1

Light is a form of energy because it has warmth

- the energy that light carries is radiative energy

Question 2

What are scientists more interested when it comes to measuring the energy of light?

Answer 2

They are interested in the rate that light transfers energy rather than the total energy it carries

Question 3

What is power? What is the unit measured?

Answer 3

Power is the rate of energy flow

- it is measured in watts

Question 4

What does white light consist of?

Answer 4

White light is made up of all the other colours (sunlight is white light)

Question 5

What does the colour black signify?

Answer 5

Black is the absence of light or colour

Question 6

What four things can matter do to light when it interacts with it?

Answer 6

1. emission - comes from a matter emitting radiative energy or a light emitting radiative energy
2. absorbtion - absorbed energy from light causes skin to warm
3. transmission - re-emission of energy
4. reflection - light bounces a) in the same direction or b) scattered

Question 7

What are the three properties of a wave?

Answer 7

1. it has a wavelength (the distance between two peaks)
2. it has frequency (the number of times per second a wave goes up and down)
3. speed (how fast the peaks travel)

Question 8

What is a particle?

Answer 8

A rigid body of mass

Question 9

What is a wave?

Answer 9

A repetitive motion of non-solid substances (water or air)

Question 10

How are light and gravity analogous?

Answer 10

Because the are both energy emitted from a source

Question 11

What is the emission source of gravity?

Answer 11

Matter

Question 12

What is the emission source of light?

Answer 12

Charge

Question 13

What is a photon?

Answer 13

A particle of light

Question 14

When do electrons move?

Answer 14

When light passes by - light carries a vibrating electric field

Question 15

How fast do electromagnetic waves travel?

Answer 15

At the speed of light

Question 16

What is the formula for the speed of light?

Answer 16

speed of light (c) = wavelength x frequency

Question 17

What does a longer wavelength mean?

Answer 17

A lower frequency

Question 18

What does a shorter wavelength mean?

Answer 18

A higher frequency

Question 19

What is Planck’s constant? What is it measured in?

Answer 19

It measures the energy of light

- It is the units of joules per second

Question 20

What is the highest frequency found in nature? What part of the spectrum does this frequency belong to?

Answer 20

The highest frequency is a zetahertz

- these are gamma rays

Question 21

What is the range of frequencies visible to humans?

Answer 21

400nm (blue) to 700nm (red)

Question 22

What is the order of frequencies in the light spectrum, going from the highest frequency to the lowest?

Answer 22

gamma rays - x-rays - UV - visible light - infrared - microwaves - radio waves

Question 23

Who first proposed the idea of the atom?

Answer 23

Democratus

Question 24

What are atoms composed of?

Answer 24

Protons, neutrons, and electrons

Question 25

What two properties to particles have?

Answer 25

They contain both mass and charge

Question 26

What two units does charge come in?

Answer 26

Positive and Negative

Question 27

What are the two properties of charge?

Answer 27

Charges cannot be cut (ex. you cannot have 0.5 positive charge) and oppositely charged particles attract, while similarly charged particles repel

Question 28

What property does every atom of a given element have?

Answer 28

They all have the same number of protons, but the numbers of their electrons can vary

Question 29

How do atoms and molecules interact with each other?

Answer 29

Through strong and weak forces

Question 30

What three phases of can matter take on?

Answer 30

1. solid phase: atoms are rigidly locked together by mutual forces 2. liquid phase: atoms experience a net force with spring-like characteristics 3. gas phase: atoms are free to move around as if free from any net force

Question 31

What is an atomic number?

Answer 31

the number of protons in a nucleus

Question 32

What is an atomic mass number?

Answer 32

the number of protons and neutrons in an atom

Question 33

What is a molecule?

Answer 33

Two or more atoms

Question 34

What is an isotope?

Answer 34

The same number of protons but a different number of neutrons

Question 35

What is sublimation?

Answer 35

Vaporization from a solid

Question 36

What is evaporation?

Answer 36

Vaporization from a liquid

Question 37

What is molecular dissociation?

Answer 37

When collisions become so violent in the atom (at high temperatures) that the chemical bonds that hold them together are broken

Question 38

What is ionization?

Answer 38

The process of stripping electrons from atoms

Question 39

Why do phases of the same material (ex. hydrogen) behave differently?

Answer 39

Because of the difference in their chemical bonds

Question 40

What is plasma?

Answer 40

It is a type of hot gas in which atoms have become ionized

Question 41

What are the two factors for determining what phase a substance takes?

Answer 41

Temperature and pressure

Question 42

What is pressure?

Answer 42

the force per unit area pushing on an object's surface

Question 43

What is spectroscopy?

Answer 43

The process of obtaining and reading a spectrum

Question 44

What are the three basic types of spectra?

Answer 44

1. continuous spectrum - the spectrum that spans all possible wavelengths without interruption 2. emission spectrum - a thin or low-density cloud of gas emits light only at specific wavelengths that depend on its composition; it produces a spectrum with bright emission lines 3. absorption spectrum - a cloud of gas between us and a lightbulb can absorb light of specific wavelengths, leaving dark absorption lines in the spectrum

Question 45

What is a chemical fingerprint?

Answer 45

the spectrum of light produced by a material (due to its specific properties)

Question 46

What is a blackbody?

Answer 46

An object that can absorb light but from which light cannot easily escape

Question 47

What does a blackbody's thermal radiation depend on?

Answer 47

Only on temperature

Question 48

What are the properties of dense objects like stars?

Answer 48

They all behave as blackbodies

Question 49

What happens when a blackbody heats up?

Answer 49

there is an increased accumulation of photons, so it radiates energy as thermal radiation (blackbody radiation) and it changes colour (from red to white hot)

Question 50

What do the laws of blackbody radiation describe?

Answer 50

How light changes with colour

Question 51

What are the two laws of blackbody radiation?

Answer 51

1. hotter objects emit more radiation per unit surface area at every wavelength 2. hotter objects emit more of their light at shorter wavelengths (high energy)

Question 52

What is the doppler effect?

Answer 52

The observation that an object's pitch (in the auditory modality) changes as a function of its distance from us

Question 53

Does the doppler effect exist in the frequency of light? How is it measured?

Answer 53

Yes | - it is measured from shifts in the wavelengths of spectral lines

Question 54

What wavelength does an object moving towards us have?

Answer 54

A blue shift (a shift to blue from the lab)

Question 55

What wavelength does an object moving away from us have?

Answer 55

A red shift (a shift to red from lab)

Question 56

What is the only information a doppler effect can give us?

Answer 56

The speed at which an object is moving towards us or away from us (not anything other than towards or away)