section 1 and 2 aqa

Question 1

Explain what causes extra particles to be created when two particles collide.

Answer 1

Energy and mass are equivalent. When two particles collide, there is a lot of energy at the point of impact. This energy is converted to mass.

Question 2

which mesons is stable?

Answer 2

none as all mesons are unstable.

Question 3

what is the lightest meson?

Answer 3

Pions.

Question 4

where was Pions and kaons discovered?

Answer 4

Cosmic rays.

Question 5

through what interaction do mesons and baryons interact

Answer 5

strong force

Question 6

what are leptons?

Answer 6

Leptons are fundamental particles that do not feel the strong nuclear force. They only really interact through the weak interaction (along with a bit of gravitational and electromagnetic force as well if they change).

Question 7

List all the decay products of the neutron. Explain why this decay cannot be due to the strong interaction.

Answer 7

Proton, electron and a electron anti-neutrino.(1MARK) The electron and the electron anti-neutrino are leptons.(1 MARK) Leptons are not affected by the strong nuclear force ,so the decay cant be due to the strong interaction.(1 MARK).

Question 8

write the quark composition of pi minus

Answer 8

ûd

Question 9

HOW DOES A FLORESCNET TUBE WORK

Answer 9

Turn on the power supply which causes a high voltage to be applied to the mercury vapour which accelerates fast free electrons which collide with the mercury atoms.

mercury electrons are then excited ,returning to ground state and UV light photons are released.

The tubes phosphorus coating absorbs UV photons and its electrons are excited , They cascade down the energy levels and visible light photon is released.

Question 10

Describe the photoelectric effect.

Answer 10

When light above a particular frequency is shone on metal , electrons are released - these released electrons are “ photoelectrons
“.

Question 11

what is the threshold frequency?

Answer 11

The minimum amount of frequency required for electrons to be emitted from the metals surface.

Question 12

why does a photon need to be of a minimum frequency to liberate an electron?

Answer 12

The energy of a photon is determined by its frequency , the photons energy must be greater than the work function in order for an electron to be emitted.

Question 13

if a photon has a frequency higher than the threshold frequency , what would occur?

Answer 13

The electron will be liberated and the remaining energy is the kinetic energy of the electron.

Question 14

if light is incident on a metal and photoelectric effect does NOT occur ,what is the effect on increasing the intensity?

Answer 14

• if it is more intense then there would be more photons incident on the metal each second.
  -However each photon still has the same amount of energy as before.
  -Therefore it still does not contain enough energy to liberate an electron.
  -No effect

Question 15

Define the work function.

Answer 15

The minimum energy required by an electron to overcome the metallic bond holding it in the metal.

Question 16

What is an electron volt?

Answer 16

The kinetic energy of an electron that has been accelerated from rest through a potential difference of 1v

Question 17

How do electrons in Atoms exist?

Answer 17

Electrons in atoms exist in discrete levels.

Question 18

How can electrons move down energy levels?

Answer 18

electrons can move down energy levels by emitting a photon

Question 19

How can electrons move up energy levels?

Answer 19

electrons can move up energy levels if they absorb a photon with the exact energy difference between the two levels

Question 20

What is the movement of an electron to a higher energy level called?

Answer 20

excitation.

Question 21

if an electron is removed from an atom what do we call this?

Answer 21

ionisation

Question 22

what is the ionisation energy

Answer 22

the energy needed to completely remove an electron from an atom from ground state(n=1)

Question 23

How to get line emission spectrum using fluorescent tubes?

Answer 23

-if you split the light from a fluorescent tube using a prism or a diffraction grating, you will get a line spectrum.
-Each line corresponds a particular wavelength of light emitted by the source
-since only certain photon energies are allowed, you only see the wavelength corresponding these energies.

Question 24

How can we get an Absorption spectrum

Answer 24

By shining white light through cool gas.

Question 25

describe a line emission spectrum

Answer 25

- series of bright lines against a black background

Question 26

describe how continuous spectra contains all possible wave length.

Answer 26

-the spectrum of white light is continuous. -if you split the light up with a prism ,the colours are merged into each other (there aren't any gaps in the spectrum). -Hot things emit a continuous spectrum in the visble and infared -All the wavelengths are allowed because the electrons are not confined to energy levels in the object producing the continuous spectrum. The electrons are not bound to atoms and are free.

Question 27

describe a absorption spectrum.

Answer 27

a continuous spectrum with black lines in it, corresponding to the absorbed wavelengths.

Question 28

define excitation

Answer 28

when an electron moves from a lower energy level to a higher energy level by absorbing energy.

Question 29

which observation show light to have a 'wave-like' character ?

Answer 29

interference and diffraction

Question 30

which observation show light to have a 'particle' character ?

Answer 30

the photoelectric effect

Question 31

What happens to the de Broglie wavelength of a particle if its momentum increases? How does this affect the particles diffraction pattern?

Answer 31

as the particles momentum increases the De Broglie wavelength decreases . This means the particles angle of diffraction decreases, and the radius of the diffraction pattern decreases

Question 32

which observation show electrons to have a 'wave-like' character ?

Answer 32

electron diffraction

Question 33

Nodes

Answer 33

A point of minimum or no disturbance(basically amplitude is = 0/no vibration occurs its a fixed point).

Question 34

Anti-Nodes

Answer 34

point with maximum amplitude(at this point it goes up and down

Question 35

tensile stress

Answer 35

Force exerted per unit cross-sectional area

Question 36

tensile strain

Answer 36

ratio of extension to original length

Question 37

area under a force extension graph

Answer 37

energy stored(work done) per unit volume

Question 38

A iodine-125 nuclide decays by an electron capture to form a tellurium nuclide. state two differences between the constituents of the iodine nucleus and the tellurium nucleus it decays into.

Answer 38

electron capture: proton absorbs an electron ,neutron is formed. tellurium nuclide has 1 more neutron. tellurium nuclide has 1 less proton

Question 39

Q: Why do large nuclei (like 208-Pb z=82) have more neutrons than protons? (Refer to forces, range, and affected particles)

Answer 39

Strong nuclear force holds nucleus together, acts on protons and neutrons, short range (~3 fm). Electrostatic (Coulomb) repulsion acts between protons, infinite range. In large nuclei, more neutrons are needed to add strong nuclear force to overcome proton repulsion and keep the nucleus stable.

Question 40

what is resolution

Answer 40

the smallest change in the quantity that is being measured that gives to a recognisable change in reading

Question 41

Name the particle believed to be responsible for mass.

Answer 41

Higgs (boson) / Higgs (particle) / Higgs (boson particle) Not graviton