Quanta And Waves Flashcards

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1
Q

In Newtonian mechanics, when can the position and momentum of any particle be found?

A

When the starting details are known

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2
Q

Quantum mechanics says that it is only possible to calculate what?

A

Probabilities

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3
Q

What does the uncertainty principle say?

A

It is not possible to measure the position and the momentum of a particle with absolute certainty

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4
Q

What does the uncertainty principle in terms of energy and time lead to?

A

The concept of quantum tunnelling

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5
Q

What is an example of quantum tunnelling?

A

Alpha decay

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6
Q

Where are alpha particles emitted from?

A

Heavy nuclei

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7
Q

What are cosmic rays?

A

High energy charged particles originating in outer space

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8
Q

What percentage of particles are protons in cosmic rays?

A

89%

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9
Q

What does quantum mean?

A

The minimum amount of any physical property involved in an interaction

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10
Q

What does the quantum theory attempt to explain?

A

Phenomena and experimental observations which could not be explained by classical physics

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11
Q

What could classical physics not explain?

A

blackbody radiation, the photoelectric effect, spectra, atomic structure and electron diffraction.

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12
Q

What did Planck propose?

A

That energy existed in individual packets or quanta rather than as a constant electromagnetic wave

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13
Q

When does the photoelectric effect occur?

A

When electromagnetic radiation is directed at a metal surface and ejects electrons from the metal.

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14
Q

When charged particles from space approach the earth what are they affected by?

A

The Earth’s magnetic field

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15
Q

What happens when cosmic rays hit the top of the atmosphere?

A

They produce showers of secondary particles, including electrons, photons, neutrinos, and muons. These particles are called a cosmic air shower

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16
Q

Where do low energy cosmic rays come from?

A

The Sun

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17
Q

Where do intermediate energy cosmic rays come from?

A

The Milky Way

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18
Q

Where are the highest energy cosmic rays thought to have come from?

A

Galactic centres but their origin is still uncertain.

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19
Q

What is the term ‘particle’ used to describe?

A

Localised phenomena that transport mass and energy

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20
Q

What is the term ‘wave’ used to describe?

A

Spread out phenomena that carry energy but no mass

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21
Q

When electrons pass through a tiny opening or slit what do the produce?

A

Diffraction fringes

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22
Q

What is black body radiation?

A

The name given to the radiation emitted by hot objects

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23
Q

What is an ideal perfect radiator?

A

Black body

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24
Q

What is the term quantum used to describe?

A

A quantity which can only exist in discrete integer values

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25
Q

When is photoemission not possible?

A

Below the threshold frequency

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26
Q

What is the minimum energy required to cause photoemission called?

A

The work function

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27
Q

In the bohr model of the atom, what does the electron orbit circumfrence have to contain?

A

A whole number (n) of de broglie wavelengths

28
Q

Does an electron gain or give off energy when it jumps to an outer orbit in an atom?

A

Gains

29
Q

Does an electron gain or five off energy when it jumps from an outer orbit to an inner orbit in an atom?

A

Give off

30
Q

What is the Bohr model able to explain?

A

Emmision line spectra and absorption line spectra

31
Q

What properties does electromagnetic radiation have?

A

Particle properties and wave properties

32
Q

What properties do electrons have?

A

Wave properties and particle properties

33
Q

What are electrons and electromagnetic radiation said to exhibit?

A

Wave-particle duality

34
Q

What properties does evidence of wave-particle duality come from?

A

Electrons behaving as particles, electron diffraction and interferance patterns

35
Q

What properties suggest that electrons are particles?

A

They have a mass and can be accelerated

36
Q

What can electromagnetic radiation produce?

A

Interferance patterns

37
Q

What provides evidence that electromagnetic radiation has wave properties?

A

The fact they produce interferance patterns

38
Q

What does Heisenberg’s uncertainty principle state?

A

It is impossible to determine accuratly both the position and the speed and direction of a quantum particle at the same time

39
Q

In what plane does unpolarised light have oscillations perpendicular to its direction of travel?

A

Every plane

40
Q

What is an example of polarisation?

A

A coating on sunglasses which cut down glare

When light is reflected from an electrical insulator such as glass or water

41
Q

Where does interference by divisions of wave front take place?

A

Between two coherent waves which originated from the same wave front

42
Q

When are waves said to be coherent?

A

If there is a constant phase difference between them

43
Q

When does destructive interference occur?

A

If the phase difference between two overlapping coherent waves is π

44
Q

When does the discharge occurs in the photoelectric effect?

A

Only when the light is above a certain threshold frequency, no matter how bright the light is

45
Q

What happens when the frequency of the light increases but not with its intensity in the photoelectric effect?

A

The kinetic energy of the ejected electrons increases

46
Q

In the photoelectric effect what does a more intense light do?

A

Releases more electrons.

47
Q

How many planes will a polarising filter or polariser allow light to pass through

A

One plane only

48
Q

How can we observe interference of light

A

A single source must be used which is passed through a single slit and then a double slit

49
Q

How are the colours seen from reflected light, such as those from petrol on water, created?

A

By interference due to division of amplitude

50
Q

What will a coherent source of waves produce?

A

Constructive interference if there is an optical path difference equivalent to a whole number of wavelengths, i.e. the waves will be in phase
Destructive interference if there is an optical path difference equivalent of an odd number, i.e. the waves will be completely out of phase

51
Q

What is damping?

A

When the amplitude of oscillation decreases to 0

52
Q

What path will a charges particle entering a uniform field at 90° to the field lines follow?

A

A circular path

53
Q

What happens if a particle enters a magnetic field at angle θ?

A

Only a component of the particles velocity will be perpendicular to the magnetic field lines

54
Q

What force is on the charged particle parallel to the magnetic field?

A

No force

55
Q

What is the radius r of a circular orbit of a charged particle moving perpendicular to a magnetic field directly proportional to?

A

The mass and velocity of the charged particle

56
Q

What is the radius r of a circular orbit of a charged particle moving perpendicular to a magnetic field inversely proportional to?

A

The magnetic induction and magnitude of the charge

57
Q

What happens when charged particles collide with nitrogen?

A

A pink light is produced

58
Q

What happens when charged particles collide with atomic oxygen?

A

A green light is produced

59
Q

What is simple harmonic motion?

A

A type of oscillation where an object vibrates about an equilibrium position under the influence of an unbalanced force which always acts towards the equilibrium position. The magnitude of the unbalanced force is proportional to the object’s displacement, but in the opposite direction

60
Q

Is there net mass transport in wave motion?

A

No

61
Q

If the amplitude of a wave increases what happens to the energy?

A

It also increases

62
Q

If the amplitude of a wave doubles , what happens to the intensity of the wave?

A

It increases 4 times

63
Q

What is a node?

A

A position of 0 disturbance on a stationary wave

64
Q

What are antinodes?

A

Points of maximum disturbance halfway between nodes

65
Q

What causes a standing wave?

A

The superposition of the incident and the reflected wave

66
Q

What is the definition for polarising?

A

An electric field vector oscillates in one plane

67
Q

What is solar wind?

A

A stream of charged particles which escape from the upper atmosphere of the Sun. These are mostly electrons, protons and alpha particles