Particles and Waves Part 1 (Forces on charged particles, standard model, nuclear reactions, spectra)

Question 1

What is the difference between fermions and bosons?

Answer 1

Fermions are matter particles - all matter in the universe is made from fermions.

Bosons are force-mediating particles - bosons are responsible for the four fundamental forces.

Question 2

Describe the right-hand-rule (for a negative charge in a magnetic field).

Answer 2

Thumb - thrust

First finger - field

Second finger - electron flow

Question 3

Is the line spectrum shown an example of emission or absorption?

Answer 3

This line spectrum is an emission spectrum (light is emitted by a particular element).

Question 4

Describe how energy is produced during a nuclear fission reaction.

Answer 4

In nuclear fission, a large unstable nuclei splits apart to form two (or more) smaller nuclei and one or more neutrons.

The total mass of the products after the reaction is less than the total mass of the products before the reaction.

This difference in mass is converted into energy (E = mc²).

Question 5

How many different types of quark are there?

Answer 5

Six.

Up, down

Charm, strange

Top, bottom

Question 6

What is a hadron?

Answer 6

A hadron is a composite particle made of quarks.

Question 7

What are the two groups of fundamental particles?

Answer 7

Quarks and leptons are the two groups of fundamental particles.

Question 8

What is the unit for potential difference?

Answer 8

The unit for potential difference is volts (V).

Question 9

Complete the following:

Moving charges experience a ………………… in a magnetic field.

Answer 9

Moving charges experience a force in a magnetic field.

Question 10

When viewing the sun using a spectroscope, this pattern is observed.

What does this pattern show and what does it tell us about the sun?

Answer 10

This is an absorption spectrum.

Different lines show the frequencies that have been absorbed by gases in the sun’s upper atmosphere.

This allows elements in the sun’s atmosphere to be identified.

Question 11

Which three quarks make up a proton?

Answer 11

A proton is made from two up quarks and one down quark.

Question 12

In the energy level diagram shown, if an electron moved from E₂ to E₀ , would the electron gain or lose energy?

Answer 12

The electron would lose energy (a photon would be emitted).

Question 13

The mass of a Higgs boson is 132 times bigger than the mass of a proton.

How many orders of magnitude bigger is the Higgs boson than the proton?

Answer 13

The Higgs boson is two orders of magnitude bigger than the proton.

(132 = 1.32 x 10^{<strong>2</strong>})

Question 14

In Physics, what is a ‘field’?

Answer 14

A field is a region where an object experiences a force.

Question 15

Which three quarks make up a neutron?

Answer 15

A neutron is made from one up quark and two down quarks.

Question 16

What happens when a matter particle and an anti-matter particle come together?

Answer 16

Annihilation (resulting in the particles beign destroyed and converted into energy).

Question 17

In a particle accelerator (such as the Large Hadron Collider), how are the particles accelerated?

Answer 17

In a particle accelerator, the particles are accelerated using an electric field.

Question 18

What are the four fundamental forces in the Standard Model?

Answer 18

The four fundamental forces in the Standard Model are

• gravitational
• electromagnetic
• strong nuclear
• weak nuclear

Question 19

A positron is the anti-particle of the electron.

In what way is the positron similar to, and different from, the electron?

Answer 19

The positron has the same mass but opposite charge from the electron.

Question 20

What name is given to the reaction shown?

Answer 20

Nuclear fission (splitting apart of a larger nucleus into smaller ‘fragments’, releasing neutrons and energy).

Question 21

What name is given to the type of spectrum shown here?

Answer 21

A continuous spectrum.

Question 22

What is the unit for energy?

Answer 22

The unit for energy is joules (J).

Question 23

What is a fermion?

Answer 23

A fermion is a matter particle.

Question 24

Which boson is responsible for the weak nuclear force?

Answer 24

The W and Z bosons are responsible for the weak nuclear force.

Question 25

Which **boson** is responsible for the **strong nuclear force**?

Answer 25

The **gluon** is responsible for the strong nuclear force.

Question 26

What is a **baryon**?

Answer 26

A **baryon** is a type of hadron, made of **three quarks**.

Question 27

What is the definition of **1 volt**?

Answer 27

**1 volt** is equivalent to **1 joule per coulomb of charge**.

Question 28

What is the unit for **frequency**?

Answer 28

The unit for frequency is **hertz** (**Hz**).

Question 29

Which **boson** is responsible for **electromagnetic force**?

Answer 29

The **photon** is responsible for electromagnetic force.

Question 30

What is a **meson**?

Answer 30

A **meson** is a type of hadron, made of **two quarks** (specifically, one matter quark and one antimatter quark).

Question 31

**Beta decay** is evidence of the existence of **which particle**?

Answer 31

Beta decay is evidence of the existence of the **neutrino**.

Question 32

In a particle accelerator (such as the Large Hadron Collider), what is used to **control the direction** of the particles?

Answer 32

In a particle accelerator, a **magnetic field** is used to **control the direction** of the particles.

Question 33

Which **boson** is responsible for **gravitational force**?

Answer 33

The **graviton** (undiscovered!) is responsible for gravitational force.

Question 34

What is meant by a **fundamental particle**?

Answer 34

A fundamental particle cannot be broken down into anything smaller.

Question 35

In diagrams showing magnetic fields, what do these symbols represent?

Answer 35

The '**cross**' show magnetic field lines going **into the page**. The '**dot**' shows magnetic field lines coming **out of the page**.

Question 36

By referring to the energy level diagram shown, explain **how many lines** would be observed in a line **spectrum** for this element.

Answer 36

There would be **6 lines**. There are **six possible transitions** for the energy level diagram shown. * E₃ to E₂E₂ to E₁E₁ to E₀ * E₃ to E₁ E₂ to E₀ * E₃ to E₀

Question 37

What is the unit for **charge**?

Answer 37

The unit for charge is **coulombs** (**C**).

Question 38

Describe the **Bohr model of the atom**. Give as much detail as possible.

Answer 38

* The nucleus is positively charged * Electrons are restricted to particular energy levels (orbits) * The further from the nucleus the electron orbits the more energy the electron must have to stay in that orbit. * electrons move between energy levels emitting (or absorbing) energy in the form of a photon

Question 39

In an energy level diagram for an atom, what name is given to **E₀**?

Answer 39

Ground state.

Question 40

What is quantity is represented by ***h f*₀ **?

Answer 40

***h f₀*** is the **work function** - minimum energy required to eject an electron from the surface of a metal.

Question 41

What is meant by **anti-matter**?

Answer 41

Anti-matter means a particle of the **same mass** but **opposite charge**.

Question 42

What name is given to the reaction shown?

Answer 42

Nuclear **fusion** (two smaller nuclei joining together, releasing energy).

Question 43

Explain, in terms of **electrons** and **energy levels**, how a spectrum like the one shown here is produced.

Answer 43

When light is shone at a particular element, **certain frequencies** of light are **absorbed**. Each **black line** indicates a particular transition where **photons of one frequency** have beenn **absorbed** and **electrons** have been raised to a **higher energy level**.

Question 44

By making reference to the energy level diagram shown, explain how a **line spectrum** is produced when viewing light emitted by a particular element.

Answer 44

* Electrons can **drop** from a **higher energy level** to a **lower one**. * Each particular 'drop' produces a **photon** of a certain **energy** and therefore of a specific **frequency**. * Different transitions (drops between energy levels) produce photons of **different energy and frequency**. * In a **line spectrum**, each line is the result of many **photons** making one particular transition. Different transitions produce different lines in the spectrum.

Question 45

Complete the following: A **stationary charge** creates ............................ field. A **moving charge** creates .............................. field.

Answer 45

A **stationary charge** creates an ***electric* field**. A **moving charge** creates a ***magnetic* field**.

Question 46

In the diagram, what do the lines represent?

Answer 46

The lines represent the **direction of force** a **positively-charged particle** would experience in that field.

Question 47

What is the unit for **force**?

Answer 47

The unit for force is **newtons** (**N**).

Question 48

What name is given to the type of spectrum shown here?

Answer 48

An **absorption** spectrum - because the black lines show the frequencies of light that have been **absorbed**. (it is also an example of a line spectrum)

Question 49

In the line spectrum shown, explain why **some coloured lines** are **brighter** than others.

Answer 49

Each line is caused by a **transition** of an **electron** from a **higher energy level** to a **lower energy level**. If a line is **brighter**, it means that **more electrons** (per second) are making that particular transition than other ones.