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AQA A Level Physics > 1.1 > Flashcards

1.1 Flashcards

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1
Q

What is a nucleon

A

The number of protons + neutrons in the nucleus

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2
Q

Proton Number

A

The number of protons in the nucleus

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3
Q

Isotope

A

Isotopes are atoms with the same number of protons and different numbers of neutrons

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4
Q

How to display an element

A

A

  X

Z

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5
Q

What does A stand for

A

Nucleon number (number of protons + neutrons)

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6
Q

What does Z stand for

A

Number of protons

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7
Q

What does X mean

A

Chemical symbol for element

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8
Q

Formula to calculate specific charge

A

Charge
________

Mass

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9
Q

Units for specific charge

A

CKg-1

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10
Q

How to calculate specific charge of a nucleus

A

Number of protons x charge of 1 proton
_________________________________________

Number of nucleons x mass

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11
Q

How to calculate specific charge of an ION

A

Net charge of ion
_________________________________

Number of nucleons x the mass

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12
Q

What is the strong nuclear force

A

The force that holds nucleons together
It overcomes the electrostatic force of repulsion between the protons

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13
Q

Points about the strong nuclear force

A
  • max range = 3-4fm
  • same effect between protons as it does between two neutrons/proton and a neutron
  • attractive force from 3-4 to 0.5fm.
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14
Q

Why are some nuclei unstable

A

When the atoms of an element have extra neutrons or protons it creates extra energy in the nucleus and causes the atom to become unbalanced or unstable

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15
Q

Beta radiation equation

A

Make sure to note about the anti neutrino: __
V

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16
Q

Gamma radiation

A

Electromagnetic radiation emitted by an unstable nucleus

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17
Q

Electromagnetic waves consist of an electric wave and a magnetic wave which travel together and vibrate:

A
  • at right angles to each other in the direction that they were travelling in
  • in phase with each other (reach peaks and troughs at the same time)
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18
Q

When are electromagnetic waves emitted?

A

When a charged particle loses energy

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19
Q

What is a photon?

A

A particle representing a quantum (smallest divisible unit) of light or other electromagnetic radiation

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20
Q

When is electromagnetic waves emitted

A
  • a fast moving electron is stopped or slows down or changes direction
  • an electron in a shell of an atom moves to a different shell of lower energy
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21
Q

How to calculate photon energy

A

Photon energy E = hf

H = Planck’s constant
F = frequency

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22
Q

How to calculate wavelength

A

Wavelength = velocity/frequency

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23
Q

What is the value of Planck’s constant?

A

6.63 x 10^-34

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24
Q

How to calculate the power of a source of light? (Written)

A

The power is the energy per second transferred by the photons

25
Q

Formula to calculate the power of a beam of light consisting of photons of frequency f

A

Power of the beam = nhf

N = number of photon passing a point per second
H = Planck’s constant
f = frequency

26
Q

What is antimatter?

A

Particles that have the same rest mass, but equal and opposite charge to their corresponding particle

27
Q

Positron

A

Particle of antimatter that is the antiparticle of the electron

28
Q

Symbol for positron

A

0
B
+1

29
Q

Thing to remember for positron equation

A

A neutrino is added

30
Q

How to positron emitting isotopes occur?

A

Placing a stable isotope (liquid or solid) in the path of a beam of protons.
Some of the nuclei in the substance absorb extra protons and therefore emit them as positrons because they have now become unstable.

31
Q

What did Dirac predict?

A

For every particle there is a corresponding antiparticle that:

  • annihilates the particle and itself if they meet, converting their total mass into photons
  • has exactly the same rest mass as the particle
  • has exactly opposite charge to the particle if the particle has a charge
32
Q

What is pair production

A

When a photon with sufficient energy passing near a nucleus/electron can suddenly change into a particle-antiparticle pair which would then separate from each other

33
Q

One electron volt definition

A

The energy transferred when an electron is moved through a potential difference of 1 volt

34
Q

How to calculate rest energy of a particle

A

E=mc2

35
Q

When does annihilation occur?

A

When a particle and its corresponding antiparticle meet and their mass is converted into radiation energy

2 photons are produced in this process

36
Q

Why are 2 photons emitted?

A

To ensure a momentum of 0 after the collision

37
Q

How to calculate the minimum energy of each photon produced

A

hf min = E0

E0 is the rest energy of the particle

38
Q

What happens in pair production

A

A photon creates a particle and a corresponding antiparticle and vanishes in the process

39
Q

How to calculate the minimum energy of the photon needed for pair production

A

hf min = 2E0

40
Q

Eg the electron has a rest energy of 0.511MeV. Therefore for park production of an electron and a positron from a photon:

A
  1. X 0.511 MeV = 1.022 MeV = 1.64 x10-13J

A photon with less energy could not therefore create a positron and an electron.

41
Q

Positron emission equation

A

A A 0
X —-> Y + B + V
Z Z-1 +1

42
Q

What happens to the electron/positron after pair production

A

They collide with another electron/positron and annihilate

43
Q

Beta decay equation

A

A A 0 __
X —-> Y + B + V
Z Z+1 -1

44
Q

Explain the process of pair production

A

When a photon interacts with an orbital electron or a nucleon within the nucleus, the energy of the photon is used to create a particle-antiparticle pair. In order to conserve momentum, the photon needs to interact with interacting particle

45
Q

Explain why pair production cannot take place if the frequency of the photon is below a certain value

A

E = hf so the energy of photon is proprtional to its frequency. When pair production occurs the energy is converted to mass according to the equation E = mc2. If the energy/frequency is below the conversion to the mass/rest energy of the particle and antiparticle pair the event will not occur.

46
Q

Gravitational fields

Acts on, range, exchange particle

A

Due to mass

  1. All masses
  2. Infinite
  3. Bosons, gravitons
47
Q

Electromagnetic

  1. Acts on
  2. Range
  3. Exchange particle
A

Due to charges

  1. Stuff that has charge
  2. Infinite
  3. Photons
48
Q

Weak nuclear force

  1. Acts on
  2. Range
  3. Exchange particle
A

Controls radioactive decay

  1. All particles
  2. 1x10-18 fm
  3. W+, W-, 20Boson
49
Q

Strong nuclear force

  1. Acts on
  2. Range
  3. Exchange particle
A

Holds the nucleus together

  1. Acts on nucleons only
  2. 3x10-15 fm
  3. Pions between nucleons,has mass + Charge
50
Q

What does an exchange particle do?

A

Transfers: energy, momentum, force and charge

51
Q

Feynman diagram for 2 protons

A

2 proton in, 2 photons out with a virtual photon

52
Q

Feynman diagram for neutron and neutrino

A

Neutron + neutrino ——> (W- boson) proton + electron

53
Q

Feynman diagram for proton and antineutrino

A

Proton + antineutrino —-> (W+ boson) neutron + positron

54
Q

Feynman diagram for beta minus decay:

A

Neutron —-> (W- boson) proton + electron + antineutrino

55
Q

Feynman diagram for beta plus decay

A

Proton —-> (W+ boson) neutron + positron + neutrino

56
Q

Feynman diagram for electron capture

A

Proton + electron —-> (W+ boson) neutron + neutrino

57
Q

Difference between W bosons and photons

A
  • W bosons have a non-zero rest mass
  • W bosons have a very short range of no more than ≈ 0.001fm
  • Are positively charged (eg W+ or W- )
58
Q

Why are photons and W boson known as force carriers?

A

Because they are exchanged when the electromagnetic force and the weak nuclear force act

AQA A Level Physics (2 decks)

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