Unit 2 - Particles And Waves Flashcards Preview

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Flashcards in Unit 2 - Particles And Waves Deck (71):
1

What does coherent mean in terms of waves?

Coherent phase difference.

2

What is produced when there is a bright fringe?

A maxima = in-phase, constructive interference.

3

What is produced at dark fringes?

A minimum = out of phase, destructive interference.

4

If wavelength is decreased what happens happens to the maxima separation?

Decreases.

5

What colour of light refracts the furthest?

Red because it has longer wavelengths.

6

What is the test for wave behaviour?

Causing an interference pattern.

7

Explain Young’s double split experiment.

- Splits one source of light into two.
- Produces coherent light waves
- Interference pattern

8

What happens when white light passes through a diffraction grating?

Central order maximum is white.
Remaining maxima are spectra.

9

Why does white light produce a white central order maximum?

All wavelengths meet in phase, constructive interference.

10

What effect does increasing the slit separation have on the interference pattern?

Decreases fringe separation.

11

What is refraction?

When light changes velocity when it passes from one material to another.

12

What is absolute refractive index?

The ratio of the speed of the speed of the incident ray in a vacuum to the speed of the refracted light in the material.

13

Angle theta (01) is always the angle in what?

Air (angle of incidence between the normal and ray of light)

14

Will a longer wavelength diffract more or less?

Less diffraction.

15

Why is the critical angle?

Angle of incidence that causes the light to refract at 90 degrees to the surface.

16

When does total internal reflection occur?

If the angle of incidence is increased above the critical angle.

17

What is irradiance?

The power per unit area.

18

What is a point source?

Source of light that appears to have no dimensions to the observer.

19

When does the irradiance of a point source decrease?

As the distance increases.

20

When is a spectrum produced?

By photons of light being emitted, as electrons make downwards transitions between energy levels within an atom.

21

Does an upward transition absorb or emit energy?

Absorb energy.

22

When will an electron make a transition?

If the energy of the absorbed photon equals the amount of energy to move between energy levels.

23

Which level is the excited state?

E1

24

Will a smaller drop on the emission spectrum produce a shorter or longer wavelength

Longer wavelength

25

What is all matter made from.

Fermions

26

What are the two types of fermions?

Quarks and leptons.

27

What are hadrons made from?

Quarks.

28

Name the two types of hadrons?

Baryons and mesons.

29

Name the force carrying particle.

Boson.

30

What is antimatter?

Identical to matter except they have opposite charge.

31

What is annihilation?

When a matter and antimatter meet they annihilate each other leaving behind energy.

32

What was discovered during beta decay?

Electron neutrino.

33

What acts on masses?

Gravity.

34

What does electromagnetism act on?

Charges.

35

What type of force acts during beta decay.

Weak nuclear force.

36

What force acts between quarks?

Strong nuclear force.

37

What is conserved during particle interactions?

Charge.

38

What is an electric field?

The region where a charge will experience a force.

39

Dehydrated do charges accelerate in an electric field?

Due to an unbalanced force.

40

What ways do the arrows point on a positive charge?

Point away.

41

What way do the arrows point on a negative charge?

Point away.

42

What does the potential difference of 2.5kV mean?

2500J needed to move 1 coulomb of charge across the electric field from one plate to another.

43

What are the three types of particle accelerators?

Linear accelerator, cyclotron, synchrotron.

44

What does a particle accelerator do?

Causes particles to collide into each other.

45

Why are particle accelerators so important?

At high energies it can recreate the conditions during the Big Bang and investigate the particles that existed.

46

What is a magnetic field?

A region that can exert a force on a charge.

47

What kind of charge creates an electric field?

Stationary charge.

48

What kind of field does a moving charge create?

Magnetic field.

49

When using the right hand rule why does the middle finger represent?

Negative charge of current.

50

What symbol is used to represent the field lines pointing into the page.

X

51

What is a (.) used to represent in terms of field lines?

Field lines point out of page.

52

What is a nuclide?

Nucleus with a specific number of protons and neutrons.

53

Define an isotope.

Nuclides with the same atomic number but different mass number.

54

When a radionuclide decays what does it emit?

Radiation or particles to become a more stable daughter product.

55

What type of nuclear fission occurs naturally?

Spontaneous nuclear fission.

56

How does induced nuclear fission occur?

Large nucleus is bombarded with neutron which splits the nucleus into smaller nuclei with the release of energy and electrons.

57

How does an induced nuclear fission reaction release energy?

The total mass before is greater than the total mass after. The loss in mass is converted into energy using E=mc^2.

58

During nuclear fission what is conserved?

Atomic and mass number

59

What is nuclear fusion?

When two smaller nuclei join to make a larger nucleus.

60

What are quanta of energy?

Fixed or discrete amount of energy, directly proportional to frequency.

61

What are photons?

Quanta of energy.

62

What is the photoelectric effect?

Photon energy is absorbed by the electron and becomes a free electron .

63

What type of emission is best for the photoelectric effect?

A UV photon.

64

What type of charges need to be present in the metal for the photoelectric effect to work?

Negative charges.

65

What does the metallic surface need to have for photoelectric emission?

Low enough work function/ threshold frequency.

66

What quarks make up a baryon?

3 quarks or 3 anti-quarks.

67

What quarks make up a messon?

1 quark and 1 anti-quark.

68

Give an example of a meson.

Pion.

69

What happens to the photoelectric current as photon energy increases?

Photoelectric current increases.

70

Define work function.

Minimum amount of energy needed to bring an electron to the surface of the metal.

71

Define threshold frequency.

Minimum frequency an incident photon needed to bring an electron the surface of the metal.