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Physics A Level COPY > Chapter 24 Particle Physics > Flashcards

Chapter 24 Particle Physics Flashcards

1
Q

What was the plum pudding model?

A

Electrons were contained in a sea of positive charge

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2
Q

What happened in Rutherfords alpha scattering experiment?

A

Alpha particles were fired at a thin metal foil
The alpha particles were deflected
Measurements were taken to see the angle at which the particles were deflected and how many were deflected

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3
Q

What observations were made during the experiment?

A

Very few alpha particles were scattered and most went straight through
Very very few particles were deflected through angles more than 90*

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4
Q

What conclusions were drawn from the experiment?

A

Most of the nucleus of an atom is empty space (because most past through)
The nucleus had a positive charge because it repelled some alpha particles

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5
Q

How did rutherford calculate the size of the nucleus?

A

He worked out that when an alpha particle is fired with energy towards the nucleus it will momentarily stop before being repelled away. If you know the kinetic energy of the alpha particle then u know how close it got to the atom. Using this you get an upper limit of the size of the nucleus. This is the distance of closes aproach

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6
Q

What is the equation for the radius of a nucleus?

A

R = r0 x A^1/3

r0 = 1.2x10^-15
A = Number of nucleuons (protons / Neutrons)
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7
Q

Atoms would seem to completely fall apart because the protons repel each other so strongly and gravity is too weak to hold them together. What is?

A

The strong nuclear force

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8
Q

What are the properties of the strong nuclear force?

A

Attractive to about 3fm

Repulsive below 0.5fm

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9
Q

What is antimatter?

A

It is the opposite of matter. Has the same mass but has the opposite charge

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10
Q

What are the 4 fundamental forces?

A

Strong Nuclear
Weak Nuclear
Electromagnetic
Gravitational

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11
Q

What does weak nuclear force do?

A

It causes beta decay

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12
Q

What conditions need to be met for gravitational force?

A

The object / Particle needs to have mass

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13
Q

What conditions need to be met for electromagnetic force?

A

The object / particle needs to have a charge

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14
Q

What is a hadron? examples

A

Particles / antiparticles that are affected by the strong nuclear force

protons, neutrons, maesons

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15
Q

What are leptons? and examples?

A

They are particles and antiparticles that are not affected by the strong nuclear force

electrons, neutrinos, muons

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16
Q

What are quarks?

A

They are what make up hadrons

17
Q

What are the 6 quarks and 6 antiquarks?

A 
Up - antiup
down - antidown
charm - anticharm
strange - antistrange
top - antitop
bottom - antibottom
18
Q

What quarks are protons made from?

A

Up, Up, Down

19
Q

What quarks are neutrons made from?

A

Down, Down, Up

20
Q

What is the charge of up?

A

+2/3

21
Q

What is the charge of down?

A

-1/3

22
Q

What is the charge of strange?

A

-1/3

23
Q

What quarks are antiprotons made from?

A

Antiup, Antiup, Antidown

24
Q

What are baryons?

A

Any hadron made with 3 quarks

25
Q

What are mesons?

A

Hadrons made from a quark and an antiquark

26
Q

What is a neutrino and what are its properties?

A

They are a tiny particle that passes through everything including the earth. They do not interract with anything. They help to explain beta decay
Properties:
Very small
No charge

27
Q

What are the two types of beta decay and what type of charged particle do they release?

A

Beta + releases a positron

Beta - releases an electron

28
Q

What causes beta decay?

A

The weak nuclear force

29
Q

What is the word equation for beta - decay?

A

Neutron ==> Proton + electron + electron antineutrino

30
Q

What is the word equation for beta + decay?

A

Proton ==> neutron + positron + electron neutrino

31
Q

Why are neutrinos / antineutrinos involved in beta decay?

A

To balance conservation at the start and end of the decay

32
Q

What happens to the quarks in beta - decay?

A

A down quark becomes an up quark

33
Q

What happens to the quarks in beta + decay?

A

An up quark becomes a down quark

34
Q

What is conserved in beta decay?

A

Charge is conserved

Mass is conserved

Physics A Level COPY (27 decks)

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