waves, quantum theory, and photons

Question 1

What is a wave?

Answer 1

A vibrating disturbance through which energy is transmitted

Question 2

How are waves described?

Answer 2

By their height (amplitude) and length (frequency)

Question 3

What is wavelength? What symbol represents it?

Answer 3

the length of the wave from peak to peak (top to top) or trough to trough (bottom to bottom)

lambda

Question 4

What is amplitude?

Answer 4

distance from the middle of the wave (line in the middle) to the peak (top)

Question 5

What is frequency?

Answer 5

the number of waves that pass through a specific point

Question 6

Waves can be measured in ______ (4)

Answer 6

meters, centimeters, nanometers, or Angstroms

Question 7

What is an angstrom?

Answer 7

A unit of length = to 10^-10 meters

Question 8

An example of the energy of electrons acting like a wave is ______

Answer 8

EM radiation (flame from a fire, rays from the sun, x-ray)

Question 9

What are the 7 different part of the EM spectrum? (7)

Answer 9

Radio, Microwaves, Infrared, Visible, Ultraviolet, X-rays, Gamma rays
Roger Makes Instruments: Violins, Ukeleles, Xylophones, and Guitars

Question 10

Which part of the EM spectrum can humans see? Which part has a longer wavelength and which has a shorter wavelength? What is the acronym for the parts of this part?

Answer 10

the visible spectrum.
red has a longer wavelength, violet has a shorter wavelength
ROYGBIV

Question 11

What is the wavelength in meters of a radio wave? Give a comparison for how big they are.

Answer 11

more than 1 meter. the size of buildings

Question 12

What is the wavelength in meters of a microwave wave? Give comparison size

Answer 12

1 to 10^-3 meters

grains of sugar

Question 13

What is the wavelength in meters of an infrared wave? Give comparison size

Answer 13

10^-3 to 7*10^-7

protozoan

Question 14

What is the wavelength in meters of a visible wave? Give comparison size

Answer 14

710^-7 to 410^-7

bacteria

Question 15

What is the wavelength in meters of an ultraviolet wave? Give comparison size

Answer 15

3*10^-7 to 10^-8

molecules

Question 16

What is the wavelength in meters of an x-ray wave? Give comparison size

Answer 16

3*10^-8 to 10^-12

atoms

Question 17

What is the wavelength in meters of a gamma ray? Give comparison size

Answer 17

less than 10^-12

atomic nuclei

Question 18

A radio wave is ____ and _____

Answer 18

long and wide

Question 19

A gama ray is _____

Answer 19

very small

Question 20

Electrons can act like ___, but they can also act like _____

Answer 20

waves

particles

Question 21

Who discovered that electrons can act like particles?

Answer 21

Max Planck

Question 22

What are quanta?

Answer 22

small amounts (packages) of EM radiation

Question 23

A quantum is the _________ that can be emitted or absorbed in the form of EM energy

Answer 23

smallest amount of energy

Question 24

What is planck’s constant? What does it do?

Answer 24

Planck’s constant is 6.626 * 10^-34 Joules per second
relates the energy in 1 quantum of EM to the frequency of that same EM (represents the connection between the wave nature of light and the particle nature of light)

Question 25

What is the equation for the energy of a quantum? What do all of the values mean?

Answer 25

E=hv or E=hc/(lambda)
E=the energy
h=planck’s constant, 6.626*10^-34
v=the frequency of the light absorbed or emitted=c/(lambda)
c=speed of light
lambda=wavelength
(hence, defines a quantum of energy, or the minimum amount of energy that can be emitted, when multiplied by the frequency of the light)

Question 26

What is the speed of light?

Answer 26

c=3*10^8 m/s

Question 27

What is quantum theory?

Answer 27

The study of matter and energy on atomic and subatomic levels

Question 28

Energy is always emitted in _____ multiples of hv

Answer 28

whole number (2 hv but not 1.9 hv)

Question 29

What is the photoelectric effect?

Answer 29

When light (that has energy above the threshold frequency) is shined on a metal surface, electrons are emitted

Question 30

For the photoelectric effect, what does a brighter light mean?

Answer 30

This means that more electrons will be emitted

Question 31

What is the threshold frequency? Why does it exist?

Answer 31

The frequency that the energy of the light must be above for electrons to be emitted for the photoelectric effect

Exists because electrons within metal atoms are held onto very tightly (metal atoms want to hold onto electrons) so for the electrons to be pushed out, there has to be a lot of light with a high enough frequency

Question 32

The beam of light that can successfully push out electrons for the photoelectric effect is a ______, which has the same formula as ______, and hence is the same as _____

Answer 32

a particle called a photon
quantum
as a quantum (a photom=a quantum)

Question 33

What are the characteristics of photons? (4)

Answer 33

1) neutral, stable, have no mass
2) interact with electrons and have energy and speed-dependent on their frequency
3) can travel at the speed of light in a vacuum
4) makes up all light and EM energy