Khan

Question 1

Electromagnetism

Answer 1

This is one form of how energy radiates through space

Question 2

Waves

Answer 2

These are disturbances within a medium or field which results in a vibration or oscillation

Question 3

Electromagnetic waves

Answer 3

These have perpendicular electric and magnetic fields that oscillate like a wave. The moving charged particle induces a magnetic field and the changing magnetic field produces an electric field. Because the fields are coupled Maxwell positted that light must be a wave independent of the source.

Given that magnetism and electricity are not physical, massive things EMR goes through anything.

Question 4

wavelength frequency relationship

Answer 4

C = λ v

where C = speed of light in a vaccum = 2.99 * 10⁸ m/s

v = frequency (1/s = Hz)

λ = wavelength (m)

Question 5

Gamma ray wavelength and frequency

Answer 5

λ = 10 ^ -17- -11

v = 10 ^ 19 - 25

This is the highest frequency EMR

Question 6

x-ray wavelength and frequency

Answer 6

λ = 10 ^ -11- -8

v = 10 ^ 17 - 19

This is the second highest frequency EMR

Question 7

UV wavelength and frequency

Answer 7

λ = 10 ^ -8- -7

v = 10 ^ 15 - 16

This is the third highest frequency EMR

Question 8

Visible light wavelength and frequency

Answer 8

λ = 4-7 * 10^-7

v = 10 ^ 15

This is the fourth highest frequency EMR

Question 9

IR wavelength and frequency

Answer 9

λ = 10 ^ -3-0

v = 10 ^ 9-15

This is the second lowest frequency EMR

Question 10

Radio wavelength and frequency

Answer 10

λ = 10 ^ 0 +

v = 10 ^ 9-

This is the lowest frequency EMR

Question 11

Light type by wavelength (least to greatest)

Answer 11

gamma rays, x-rays, UV, visible, IR, radio

Question 12

Light type by energy (L-H)

Answer 12

Radio, IR, visible, UV, X-Rays, gamma rays

Question 13

Photon Energy

Answer 13

E(photon) = h * v where h = Planck’s constant = 6.626 * 10^-34

Question 14

Rules for constructive/destructive interference

Answer 14

For constructive interference the change in position is d = n*λ

For destructive interference it is d = nλ/2 this is pi shifting because the light is pi radians out of sync

Question 15

If light were particles what would Young’s double split look like

Answer 15

The particles of light would travel through the slits and not diffract or interfere

Question 16

Distance between travel paths of bright spots for interference

Answer 16

This distance is equal to one wavelength. It is NOT the distance between the bright spots but the distance of travel paths

Question 17

Distance between bright spots formula

Answer 17

x = dsinθ = m λ

x = distance between bright spots

θ = angle from the center to the bright spot.

d = distance between slits

m= mode/peak #

Question 18

Why do diffraction gratings create dots

Answer 18

This is because at every point where there is not perfectly constructive interference there are equal but opposite wave points summating which create destructive interference.

Question 19

Huygen’s Principle

Answer 19

This says that every point on a wavefront can be treated like a series of tiny propagation points. Thus if you have a single slit you will have a diffraction pattern because the part of the wavefront that makes it through the hole propagates with other wavefronts to constructively interfere

Question 20

wavelength relationship for two mediums

Answer 20

λ_B = λ_a V_B/V_A = λ_A n_A/n_B

This says that the wavelength within medium B is given by the incident wavelength times the ratio of the refractive index of the first medium to the second medium.

Question 21

Thin film interference criterion destructive and constructive

Answer 21

Constructive 2t = mλ_B = m λ_a V_B/V_A = m λ_A n_A/n_B

This says that twice the thickness of the thin film is equal to integers (m) of the wavelength fo light within the thin film medium

Destructive 2t = (1/2)mλ_B = m λ_a V_B/2V_A = m λ_A n_A/2n_B

Question 22

Reflection types

Answer 22

Specular reflection refers to reflection that occurs on a flat surface so the incident and reflected rays are very predictable and related.

Diffuse reflection occurs on bumpy or uneven surface where the various directions of reflected rays interfere to produce colors

Specular and diffuse reflection happens on shiny things where parts are white (specular reflection) and others diffuse only the color of the object

Question 23

Index of refraction

Answer 23

n = C/V

Question 24

Special relativity E (electron)

Answer 24

E²=p² + KE² = p²c² + m²c⁴ You can use this to find the momentum of a photon by using plancks equation for energy and the relationship between wavelength, frequency, and the speed of light.

Question 25

momentum of a photon

Answer 25

p = h/λ

Question 26

Photoelectric effect

Answer 26

This is the emission of electrons from the surface of a metal or other material with electrons in the conductance band when interacting with EMR. The process is photoemission and the e are photoelectrons

Question 27

What is the relationship between a wave and KE

Answer 27

KE is proportional to amplitude. For light KE is proportional to frequency and not the amplitude (luminosity) but amplitude of light is proportional to more photoemissions so more charge transfer

Question 28

Photoemission threshold frequency

Answer 28

This is the idea that for photoemissions to occur that there is some critical frequency of incident light that must be met.

ϕ/h = ν₀ where ϕ is proportional to the bond energy of the electron that is emitted.

Question 29

Louis de Broglie Idea

Answer 29

Broglie said that if light is wave or particle depending on how we treat it, why would an electron differ?

Question 30

de Broglie wavelength

Answer 30

λ_e = h/p where p = momentum of electron

Question 31

what is the meaning of ψ(x)?

Answer 31

In theory it is the position of a particle but it ends up being imaginary. we do know that the absolute value of ψ(x)² is proportional to P(e^-) @ (x,y,z,t)

and we know that ψ(x) collapses at measurements

Question 32

three ways that electrons and light interact for photoemission

Answer 32

electrons will only change energy level if the incoming energy = hn where n are the varying modes and the energy is above the resonant frequency for release.

Electrons have a more negative potential energy closer to the nucleas. If the PE is positive the electron will be ejected.

If neither of the above criterion are met then the EMR goes through the electron.