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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)

Study These Flashcards
A

The power is the energy per second transferred by the photons

25
Formula to calculate the power of a beam of light consisting of photons of frequency f
Power of the beam = nhf N = number of photon passing a point per second H = Planck’s constant f = frequency
26
What is antimatter?
Particles that have the same rest mass, but equal and opposite charge to their corresponding particle
27
Positron
Particle of antimatter that is the antiparticle of the electron
28
Symbol for positron
0 B +1
29
Thing to remember for positron equation
A neutrino is added
30
How to positron emitting isotopes occur?
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
What did Dirac predict?
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
What is pair production
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
One electron volt definition
The energy transferred when an electron is moved through a potential difference of 1 volt
34
How to calculate rest energy of a particle
E=mc2
35
When does annihilation occur?
When a particle and its corresponding antiparticle meet and their mass is converted into radiation energy 2 photons are produced in this process
36
Why are 2 photons emitted?
To ensure a momentum of 0 after the collision
37
How to calculate the minimum energy of each photon produced
hf min = E0 E0 is the rest energy of the particle
38
What happens in pair production
A photon creates a particle and a corresponding antiparticle and vanishes in the process
39
How to calculate the minimum energy of the photon needed for pair production
hf min = 2E0
40
Eg the electron has a rest energy of 0.511MeV. Therefore for park production of an electron and a positron from a photon:
2. 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
Positron emission equation
A A 0 X —-> Y + B + V Z Z-1 +1
42
What happens to the electron/positron after pair production
They collide with another electron/positron and annihilate
43
Beta decay equation
A A 0 __ X —-> Y + B + V Z Z+1 -1
44
Explain the process of pair production
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
Explain why pair production cannot take place if the frequency of the photon is below a certain value
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
Gravitational fields Acts on, range, exchange particle
Due to mass 1. All masses 2. Infinite 3. Bosons, gravitons
47
Electromagnetic 1. Acts on 2. Range 3. Exchange particle
Due to charges 1. Stuff that has charge 2. Infinite 2. Photons
48
Weak nuclear force 1. Acts on 2. Range 3. Exchange particle
Controls radioactive decay 1. All particles 2. 1x10-18 fm 3. W+, W-, 20Boson
49
Strong nuclear force 1. Acts on 2. Range 3. Exchange particle
Holds the nucleus together 1. Acts on nucleons only 2. 3x10-15 fm 3. Pions between nucleons,has mass + Charge
50
What does an exchange particle do?
Transfers: energy, momentum, force and charge
51
Feynman diagram for 2 protons
2 proton in, 2 photons out with a virtual photon
52
Feynman diagram for neutron and neutrino
Neutron + neutrino ——> (W- boson) proton + electron
53
Feynman diagram for proton and antineutrino
Proton + antineutrino —-> (W+ boson) neutron + positron
54
Feynman diagram for beta minus decay:
Neutron —-> (W- boson) proton + electron + antineutrino
55
Feynman diagram for beta plus decay
Proton —-> (W+ boson) neutron + positron + neutrino
56
Feynman diagram for electron capture
Proton + electron —-> (W+ boson) neutron + neutrino
57
Difference between W bosons and photons
- 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
Why are photons and W boson known as force carriers?
Because they are exchanged when the electromagnetic force and the weak nuclear force act

AQA A Level Physics (2 decks)

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