Matter And Radiation

Question 0

How are electrons held in the atom?

Answer 0

Their negative charge attracts the positively charged nucleus through the electrostatic force

Question 1

What is a nucleon?

Answer 1

A proton or neutron in the nucleus

Question 2

What is an isotope?

Answer 2

Atoms of the same element with different numbers of neutrons

Question 3

Why must the protons remain the same in an isotope?

Answer 3

Otherwise it would be an atom of a different element

Question 4

What is the nucleaon number?

Answer 4

The total number of protons and neutrons in the atom

Question 5

What is specific charge?

Answer 5

Charge dived by mass

Question 6

What does the strong nuclear force do?

Answer 6

Overcomes the electrostatic force of repulsion between protons and keeps the protons and neutrons together

Question 7

When does the strong force not hold the neutrons and protons together?

Answer 7

In an unstable nuclei

Question 8

What is the range of the strong nuclear force?

Answer 8

3-4 femtometers

Question 9

True or false - the strong nuclear force only works on two protons?

Answer 9

False - It has the same effect on two protons, two neutrons or a proton and a neutron

Question 10

At what distance will it attract?

Answer 10

Between 0.5 fm and 3-4fm - any distance before 0.5fm it will repel

Question 11

What is alpha decay?

Answer 11

When an alpha particle ( 2 protons and 2 neutrons) is emitted from a nucleus

Question 12

What is beta decay?

Answer 12

When a neutron in the nucleus changes into a proton. A beta ( electron) is emitted along with an anti neutrino

Question 13

What is gamma radiation?

Answer 13

It is electromagnetic radiation with no mass or charge. It occurs when an atom has too much energy, following an alpha or beta emission.

Question 14

How were neutrinos and anti neutrinos detected?

Answer 14

When scientists measured the energy of beta particles emitted, the results varied up to a maximum. Some of the energy was being carried away by mysterious particles - neutrinos and antineutrinos

Question 15

What is light often expressed in?

Answer 15

Nanometers ( 1x10-9)

Question 16

what is the wavelength of visible light ?

Answer 16

400nm - 700nm

Question 17

what does an electromagnetic wave consist of?

Answer 17

an electric wave and magnetic wave that travel at 90 degrees to each other and the direction of energy. They are also in phase

Question 18

what is a photon ?

Answer 18

when electromagnetic waves are emitted, they are emitted in bursts, each burst is a packet of energy - a photon

Question 19

what does a laser beam consist of?

Answer 19

photons of the same frequency

Question 20

what is the power of a laser beam?

Answer 20

Energy per second transferred by the photons

Question 21

What happens when matter and antimatter meet?

Answer 21

They destroy each other releasing radiation - Annihilation

Question 22

What radiation is released when a positron and electron meet?

Answer 22

Gamma photons

Question 23

How does a PET scanner work?

Answer 23

A positron emitting isotope is administered and som of it reaches the brain. A positron reaches an electron, emits photons and a computer creates an image

Question 24

How are positron emitting isotopes manufactured?

Answer 24

A stable isotope is placed in a path of a beam of protons. Some of the nuclei gain protons and become unstable.

Question 25

What are the similarities and differences of particles and antiparticles?

Answer 25

They have the same rest mass but exactly the opposite charge

Question 26

What is pair production?

Answer 26

When a photon with sufficient energy changes into a particle-antiparticle pair which then separates from each other

Question 27

What is 1 electron volt?

Answer 27

The energy transferred when an electron is moved through a potential difference of 1 volt

Question 28

How was the positron discovered?

Answer 28

In a cloud chamber with a magnetic field, beta decay shows an electron bending towards positive. Carl Anderson noticed a particle bend towards the negative - a positron

Question 29

What happens when two objects interact?

Answer 29

They exert equal and opposite forces on each other

Question 30

What does the weak nuclear force do?

Answer 30

Neutrons to change into photons in beta- decay and vice versa for beta+

Question 31

What particle is exchanged by the weak nuclear force?

Answer 31

W boson

Question 32

What are the differences between w bosons and photons?

Answer 32

They have a non-zero rest mass, very short range of around 0.001fm and are positively or negatively charged