Particles and Waves Flashcards

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1
Q

Bohr model of the atom – Ionisation level

A

The energy level an electron is in when it has zero potential energy and can escape from the atom.

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2
Q

Fraunhofer lines

A

Absorption lines in the spectrum of sunlight. These give evidence for the composition of the suns outer atmosphere

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3
Q

Absolute refractive index

A

The ratio of the speed of light in a vacuum to to the speed of light in a medium

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4
Q

Irradiance

A

Power per unit area I=P/A

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5
Q

Bosons

A

These are the force mediating particles. Photons (electromagnetic force), W and Z bosons (weak nuclear force), gluons (strong nuclear force) & Higgs boson

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6
Q

Snell’s Law

A

n = sinθ1/sinθ2 = λ12 = v1/v2

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7
Q

Emission spectrum

A

Range of frequencies emitted when electrons fall to lower energy levels. Each element has a unique emission spectrum.

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8
Q

Point source of light

A

A source of light coming from a single point and giving off light in all directions e.g. small light bulb or a distant star.
I = k/d2 for a point source. I1 d1^2= I2 d2^2

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9
Q

Absorption spectrum

A

Range of frequencies absorbed when electrons rise to higher energy levels. Each element has a unique absorption spectrum.

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10
Q

Interference

A

This is evidence for the wave model of light

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11
Q

Baryons

A

Hadrons consisting of 3 quarks

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12
Q

Orders of magnitude

A

1x103 is 3 orders of magnitude smaller than 2.4x106

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13
Q

Photoelectric effect

A

This is evidence for the particle model of light. Photons of a sufficient energy can eject electrons from the surface of a material (photoemission).

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14
Q

What does E = mc2 represent?

A

In nuclear fission and fusion reactions mass is lost. This lost mass is converted into energy

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15
Q

Mesons

A

Hadrons consisting of quark - anti-quark pairs

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16
Q

Nuclear Fusion reactors

A

Require charged particles at very high temperature (plasma) which have to be contained by magnetic fields

17
Q

Coherent Waves

A

Waves that have the same frequency and constant phase difference

18
Q

Fermions

A

These are the matter particles. Consisting of quarks (Six types: up, down, charm, strange, top, bottom) and leptons (electron, muon and tau, together with their neutrinos).

19
Q

Define electric field

A

A region where a charged particle experiences a force

20
Q

Threshold Frequency

A

Minimum frequency of a photon required for photon emission

21
Q

Beta decay

A

This was the first evidence for the neutrino

22
Q

Define voltage (potential difference)

A

V=W/Q
Work don per coulomb of charge

23
Q

Hadron

A

Composite particle consisting of quarks.

24
Q

Relationship between refractive index and critical angle

A

sin θc = 1 / n

25
Q

Work Function

A

Minimum energy of photon required for photon emission

26
Q

Right hand rule for finding the direction of the force on charged particles moving in a magnetic field.

A

First finger = Direction of magnetic field (N to S)
Middle finger = direction of electron current.
Thumb = direction of the force on the particle.

27
Q

Refractive index and frequency relationship

A

Refractive index of a medium increases as the frequency of incident radiation increases.

28
Q

Constructive Interference

A

Occurs when 2 waves with a phase difference of an integer multiple of wavelengths meet and combine. Path difference =m λ

29
Q

Critical Angle

A

The angle of incidence when the angle of refraction is equal to 90 degrees.

30
Q

Ek=hf-hfo

A

Electron kinetic energy=energy of photon - work function

31
Q

Electric field patterns for single point charges.

A

A positive charged has lines uniformly coming out from a single point with arrows pointing out the way, negative charge lines should be uniformly surrounding the charge with arrows pointing in the way

32
Q

Total internal reflection

A

This occurs whenever the angle of incidence is greater than the critical angle.

33
Q

Destructive Interference

A

Occurs when 2 waves with a phase difference of an integer multiple of 1/2 wavelengths meet and combine. Path difference = (m+1/2) λ

34
Q

Diffraction grating formula
m λ = d sin θ

A
m = order of maximum
λ = wavelength of source 
d = distance between slits
θ = angle from the central (zero order) maximum
35
Q

Electric field patterns for pairs of point charges.

A

If both charges are negative all field lines surrounding will push each other away,
If one negative one positive the field lines go from negative to positive

36
Q

Electric field pattern between two charged parallel plates.

A

Negative charges attract the positives so field lines go towards them

37
Q

Bohr model of the atom - Ground State

A

The lowest energy level and electron can be in. This corresponds to the level closest to the nucleus.