PARTICLES AND WAVES - Standard model and fields

Question 1

Describe Bohr model of an atom

Answer 1

Electrons orbit the nucleus in orbits
that have a set size and energy.

The energy of the orbit is related to its size.
The lowest energy is found in the smallest orbit.

Radiation is absorbed or emitted when
an electron moves from one orbit to another.

Question 2

Fundamental particles can be split into two main groups:

Answer 2

Fermions and bosons

Question 3

Fermions are particles which have mass and can be split into two types

Answer 3

Baryons and Leptons

Question 4

Describe Beta decay

Answer 4

• Neutron in nucleus of atom
• Down Quark converts to up
• Neutron is now a proton
• Weak force W boson is required for
  conservation of charge
• An electron (beta particle) and electron
  antineutrino are produced

Question 5

The Standard Model is

Answer 5

a model of fundamental particles and interactions

Question 6

he first evidence for the neutrino …

Answer 6

Beta decay

Question 7

Hadrons are

Answer 7

composite particles made of quarks.

Question 8

Baryons are …

Answer 8

made of three quarks.

Question 9

Mesons are

Answer 9

made of quark–antiquark pairs.

Question 10

bosons are

Answer 10

Force-mediating particles

Question 11

Force-mediating particles are bosons:

Answer 11

photons (electromagnetic force),
W- and Z-bosons (weak force), and
gluons (strong force)

Question 12

Difference between electric fields and gravitational fields

Answer 12

The only difference is that two objects with mass will always attract each other.

Question 13

Charges can either

Answer 13

repel or attract

Question 14

A charged particle in an electric field will experience …

Answer 14

a force

Question 15

Rule 1 for electric fields

Answer 15

Electric Field Lines always point from positive to negative.

They follow the path a positive charge would move.

Question 16

Rule 2 for electric fields

Answer 16

Electric Field Lines always enter and leave the charge perpendicularly.

Question 17

Rule 3 for electric fields

Answer 17

Electric Field Lines never cross

Question 18

Rule 4 for electric fields

Answer 18

The closer together the electric field lines
The stronger the electric field

Question 19

potential difference is …

Answer 19

Potential difference is the number of Joules per Coulomb

Question 20

Moving charges create ………… ………….. in the ……… ……….. ………. These magnetic fields exert ………… on ……. ……. ……. …….. in the field.
Remember ……… is the flow of electrons

Answer 20

Moving charges create magnetic fields in the space around them. These magnetic fields exert forces on any other moving charge in the field.
Remember current is the flow of electrons

Question 21

The direction of the magnetic field depends on

Answer 21

the direction of conventional current.

Question 22

Newton’s laws and relativity equations can’t be applied to atomic, nuclear and sub-nuclear particles. Which branch of physics or theory must be used instead?

Answer 22

Quantum mechanics/ theory

Question 23

What is the order of magnitude planck length

Answer 23

10 - 35

Question 24

In which year did geiger and Marsden carry out the gold foil experiment?

Answer 24

In a 1909 experiment, Geiger and Marsden discovered that the metal foils could scatter some alpha particles in all directions, sometimes more than 90°. This should have been impossible according to Thomson’s model. According to Thomson’s model, all the alpha particles should have gone straight through.

Question 25

What is antimatter

Answer 25

Antimatter is the same as ordinary matter except that it has the opposite electric charge

Question 26

What is the difference between a positron and electron

Answer 26

The primary difference between an electron and a positron lies in their charge. While an electron carries a negative charge, a positron carries a positive charge. However, they share the same mass and spin, making them antiparticles of each other.

Question 27

What happens when a particle and its antimatter particle meet

Answer 27

When matter and antimatter collide, the particles destroy each other, with a huge energy release

Question 28

All particles are classed as either fermions or bosons what is the difference

Answer 28

fermions are the composites of matter bosons are force carrying particles

Question 29

What quarks make up a neutron and a proton

Answer 29

Protons contain two up quarks and one down quark. Neutrons contain one up quark and two down quarks.

Question 30

What holds the quarks together

Answer 30

The strong force

Question 31

What was the first evidence for the neutrino

Answer 31

The emission of beta radiation provides evidence that neutrons and protons are made up of quarks. Beta ( ) decay is the release of an electron by the change of a neutron to a proton.

Question 32

P is

Answer 32

proton

Question 33

n is

Answer 33

neutron

Question 34

e is

Answer 34

electron

Question 35

v is

Answer 35

neutrino

Question 36

_ V

Answer 36

antineutrino

Question 37

_ e

Answer 37

positron

Question 38

_ p

Answer 38

antiproton

Question 39

_ n

Answer 39

antineutron

Question 40

State the difference between a hadron and a lepton in terms of the type of force experienced by each particle

Answer 40

Leptons are spin 1/2 particles that do not interact via the strong force. The electron, muon, and the electron and muon neutrinos are examples. Hadrons are particles that interact via the strong force.

Question 41

Give one example of a hadron and one example of a lepton

Answer 41

Proton, Neutron, Antiproton, and Antineutron

Question 42

Briefly state any differences between the 'strong' and 'weak' nuclear forces.

Answer 42

strong force has a range of less than 10^-14 m and weak force has a range of less than 10^-17 m

Question 43

Give an example of a particle decay associated with the weak nuclear force

Answer 43

Beta decay

Question 44

Which of the 2 forces strong and weak acts over the greater distance

Answer 44

strong force

Question 45

Describe electric field

Answer 45

Electric fields are set up by charges and show the direction of force on a positive charge

Question 46

Name the cause of the field for the following Gravity Electric Magnetic

Answer 46

Mass Charge Movement of charge

Question 47

If a charge Q is accelerated by potential V it has ....

Answer 47

work done. W = QV

Question 48

When an electron moves through a magnetic field it experiences a force. Why?

Answer 48

This is because the movement of the electron is itself producing a field. The two magnetic fields interact with each other and cause the electron to change direction.

Question 49

Force on an electron in magnetic field is

Answer 49

perpendicular to motion and the magnetic field

Question 50

If the charge is moving in the same plane and in either the same or opposite direction to the magnetic field then ... what happens?

Answer 50

there is no force acting on the charge (velocity is unchanged)

Question 51

A charged particle placed in a magnetic field will change direction. What does this mean

Answer 51

This means it will accelerate without gaining Kinetic Energy.