chapter 24 - Particle physics

Question 1

What type of particles were used in Rutherford’s scattering experiment?

Answer 1

Alpha particles

Question 2

What power of 10 is the diameter of a nucleus?

Answer 2

10^-15m

Question 3

What power of 10 is the diameter of an atom?

Answer 3

10⁻¹⁰m

Question 4

What material was used as a target in Rutherford’s scattering experiment?

Answer 4

Gold foil, a few atoms thick

Question 5

What was measured in Rutherford’s scattering experiment?

Answer 5

The angle of deflection of the alpha particles.

Question 6

What happened to most of the alpha particles in Rutherford’s scattering experiment?

Answer 6

They passed straight through the foil (with very little scattering).

Question 7

What proportion of alpha particles were scattered in Rutherford’s scattering experiment?

Answer 7

Around 1 in 2000

Question 8

What proportion of alpha particles were deflected by more than 90° in Rutherford’s scattering experiment?

Answer 8

Around 1 in 10,000

Question 9

What was concluded due to most of the alpha particles passing straight through the gold foil Rutherford’s scattering experiment?

Answer 9

Most of the atom is empty space with most of the mass concentrated in a small nucleus.

Question 10

What was concluded due to some alpha particles being scattered in Rutherford’s scattering experiment?

Answer 10

The nucleus is positively charged.

Question 11

How did Rutherford estimate the maximum radius of the nucleus?

Answer 11

He equated the KE of the alpha particle to the electric potential energy at closest approach to the nucleus.

Question 12

What is a nucleon?

Answer 12

A proton or neutron.

Question 13

What is an atomic mass unit?

Answer 13

One twelfth of the mass of a neutral carbon 12 atom.

Question 14

How has the radius of the nucleus been measured?

Answer 14

By the diffraction of fast moving electrons.

Question 15

What is R in R = r₀A^(1/3)?

Answer 15

The radius of the nucleus.

Question 16

What is r₀ in R = r₀A^(1/3) roughly equivalent to?

Answer 16

The radius of a proton.

Question 17

What is A in R = r₀A^(1/3)

Answer 17

Nucleon number.

Question 18

What force holds protons and neutrons together in the nucleus?

Answer 18

The strong nuclear force.

Question 19

What is the maximum range of the strong nuclear force?

Answer 19

~3fm

Question 20

Below what distance is the strong nuclear force repulsive?

Answer 20

0.5fm

Question 21

Which group of particles are subject to the weak nuclear force but not the strong nuclear force?

Answer 21

Leptons

Question 22

What is the quark composition of a meson?

Answer 22

One quark and one antiquark

Question 23

Which force do Hadrons decay by?

Answer 23

The weak nuclear force.

Question 24

What is the quark composition of a Baryon

Answer 24

Three quarks

Question 25

What is a neutrino?

Answer 25

A lepton with no charge and a tiny mass.

Question 26

Why doesn't a neutrino experience the electromagnetic force?

Answer 26

They have no charge..

Question 27

What is the quark composition of a neutron?

Answer 27

up down down (udd)

Question 28

What is the quark composition of a proton?

Answer 28

up up down (uud)

Question 29

What is the quark composition of an anti-baryon?

Answer 29

Three antiquarks

Question 30

Name the two types of hadron.

Answer 30

baryons and mesons

Question 31

What force hold quarks together in hadrons?

Answer 31

The strong nuclear force.

Question 32

What is the family of particles that are subject to both the strong and weak nuclear force?

Answer 32

Hadrons

Question 33

What type of particle are nucleons?

Answer 33

Baryons

Question 34

How does a proton compare to an antiproton?

Answer 34

The have the same mass but opposite charge.

Question 35

How does an electron compare to a positron?

Answer 35

The have the same mass but opposite charge.

Question 36

What is the antiparticle of the electron?

Answer 36

Positron.

Question 37

What type of particle are there millions of passing through your body every second?

Answer 37

Neutrinos

Question 38

Describe beta minus decay.

Answer 38

A neutron in an unstable nucleus decays into a proton

Question 39

Describe beta plus decay.

Answer 39

A proton in an unstable nucleus decays into a neutron

Question 40

What quark transformation occurs during beta minus decay?

Answer 40

A down quark (in a neutron) turns into an up quark (in a proton)

Question 41

What quark transformation occurs during beta plus decay

Answer 41

An up quark (in a proton) turns into an down quark (in a neutron)