P3 - Edexcel Past Paper Question

Front 1

An isotope above the stability cure will undergo beta minus decay because it has... (1 mark)

Back 1

1)too many neutrons

Front 2

Describe the arrangement of quarks in a proton (2 marks)

Back 2

1)made up of three up and down quarks

2)two up and a down

Front 3

Explain what happens to a nucleus during beta plus decay (2 marks)

Back 3

1)proton changes to a neutron and positron/anti-electron is emitted

2)an up quark changes to a down quark

3)proton number goes down by one and neutron number goes up by one

Front 4

Describe how the average kinetic energy of the particles of the gas changes as the temperature of the gas increases (2 marks)

Back 4

1)average KE increases as the temperature increases

2)idea of proportionality/KE doubles when the temperature doubles

3)when temperature is in Kelvin/K

Front 5

What type and size of image is produced by a converging lens (1 mark)

Back 5

1)either real or virtual

2)either magnified or diminished

Front 6

Describe how the power of a lens is related to its shape (2 marks)

Back 6

1)greater refraction with a thicker lens

2)gives greater/ larger power

Front 7

what must the half-life or an iodine-123 tracer be (1 mark)

Back 7

1)a few days

Front 8

Pellets which contain radium-223 can be put inside the body to treat cancers. Radium-223 has a half-life of 11.4 days and emits alpha radiation. Explain why radium-223 is suitable for the use inside the body to treat cancers (3 marks)

Back 8

1)alpha is highly ionising

2) the radiation destroys cancers/ tumours

3)alpha particles do not penetrate very far so cannot damage other cells in the organ

4)half-life is long enough for the treatment to take effect

5)the half-life is short enough so the pellets don't need to be removed

Front 9

Radiotherapy is often used for palliative care when cancers are incurable. Explain how using radiotherapy in this way is helpful to patients. (2 marks)

Back 9

1)it reduces the size of the tumour/cancer

2)reduces pain/relieves symptoms

3)extends life expectancy/improves quality of life

Front 10

Explain why a CT scan of the chest gives a much higher dose of radiation than a chest X-ray

Back 10

1)CT scan lasts much longer/X-ray is short exposure

2)a CT scan is a series of X-rays

3)the intensity of radiation for CT scans is higher tan for normal X-rays

Front 11

Justify the use of medical procedures which give patients large doses of radiation (2 marks)

Back 11

1)the benefits outweigh the risks

2)it is non-invasive/not painful

3)more accurate diagnosis

Front 12

State the total momentum of the gamma rays after the annihilation (1 mark)

Back 12

1) zero

Front 13

Explain how charge is conserved in a positron-electron annihilation (2 marks)

Back 13

1)positron charge is +1 and electron charge is -1 so the total charge before annihilation is zero

2)gamma rays have no charge

Front 14

Compare the design and use of particle accelerations used in international scientific research with particle accelerators used in hospitals (6 marks)

Back 14

1)Particle accelerators use

-charged particles; magnetic fields; high frequency alternating voltages; collisions; centripetal force

2)Hospital particle accelerators

-cyclotrons; small, size of a garage; fast moving particles hit target; particles absorbed by nuclei; produce isotopes with short half-lives; only a few people needed to work them

3)Research particle accelerators

-cyclotrons; large hadron collider, CERN; very large, LHC more than 2km across; use superconducting electromagnets; accelerate particles close to the speed of light; use hundreds of research scientists; make particles collide; try to discover new particles (higgs boson)

Front 15

Suggest why people are not scanned with X-rays in an airport but have X-rays in a hospital (2 marks)

Back 15

1)X-rays are harmful to health

2)they can mutate cells/cause cancer

3)hospital use is essential

Front 16

Security people work near the X-ray machine. Explain how they are protected from the X-rays (2 marks)

Back 16

1)lead casing/shielding

2)absorbs X-rays

Front 17

Explain what is meant by thermionic emission (2 marks)

Back 17

1)cathode is heated (filament/wire heated)

2)electrons are given enough energy

3)electrons escape from the surface

Front 18

At -273 degrees the particles in a gas are... (1 mark)

Back 18

1)stationary

Front 19

A weather balloon is filled with helium. When released the balloon rises rapidly to a height of 30,000m above the earth. explain how the helium gas exerts a pressure on the balloon (3 marks)

Back 19

1)particles collide

2)with the sides of the balloon

3)causing a force/ change in momentum

Front 20

What is an advantage of using a substance with such a short half-life (1 mark)

Back 20

1)minimises patients exposure to radioactivity

Front 21

What is a disadvantage of using a substance with such a short half-life (1 mark)

Back 21

1)has to be produced close to the area it will be used

Front 22

When a positron meets an electron they annihilate each other. Explain how this enables the site of the tumour to be located (4 marks)

Back 22

1)gamma rays are emitted

2)2 gamma rays directly opposite

3)in opposite directions

4)momentum is conserved

5)detectors/sensors placed around te patient

6)simultaneous detection

Front 23

Describe in terms of quarks, how beta plus particles are emitted from the nuclei of some atoms and beta minus particles are emitted from the nuclei of others (6 marks)

Back 23

1)protons and neutrons are made up of quarks

2)quarks can change

3)proton made up of uud

4)neutron made up of udd

5)for beta plus a u changes to a d

6)for beta minus a d changes to a u

7)for beta plus a proton changes to a neutron

8)for beta minus a neutron changes to a proton

Front 24

A cyclotron accelerates charged particles. Describe the shape of the path a charged particle takes in a cyclotron (1 mark)

Back 24

1)circular

Front 25

Explain how radioactive isotopes can be produced using cyclotrons (3 marks)

Back 25

1)fast moving protons

2)bombard/collide with/are absorbed by a nuclei

3)which produces and unstable nuclei

Front 26

In an inelastic collision there is conservation of...(1 mark)

Back 26

1)momentum

Front 27

State why momentum has the unit kg.m/s (1 mark)

Back 27

1)momentum=mass x velocity

2)mass is kg and velocity is m/s

Front 28

Air molecules in a cylinder move randomly. Describe how these air molecules exert a pressure on the cylinder (2 marks)

Back 28

1)collisions hit off/bounce off and exert a force with the walls of the cylinder

Front 29

The X-rays that have the most energy have the: A)greatest mass, B)highest frequency, C)highest speed or D)longest wavelength (1 mark)

Back 29

B)highest frequency

Front 30

Ionising radiations are emitted by unstable nuclei. which particle has the same mass as but opposite charge to a beta plus particle: A)electron, B)positron, C)proton or D)neutron

Back 30

A)electron

Front 31

Suggest why a beta particle will travel further in air than an alpha particle (2 marks)

Back 31

1) the ionisation is different-alpha is more ionising

2)the masses are different

3)alpha is bigger than beta

4)alpha hits more air particles

5)alpha loses its energy in a shorter distance

Front 32

Following the radioactive decay of a nucleus, the nucleus might undergo some rearrangement, losing energy as...(1 mark)

Back 32

1)gamma radiation

Front 33

Some unstable nuclei decay by emitting beta minus radiation. describe the process of beta minus emission. (3 marks)

Back 33

1)neutron decays/changes

2)to become into a proton

3)plus an electron

Front 34

Explain what happens to the mass number and the atomic number of a nucleus when beta minus emission occurs (3 marks)

Back 34

1)mass number doesn't change

2)because same number of quarks

3)atomic number goes up by ones

4)because there is an extra proton

Front 35

An electron and a positron collide and annihilate each other. Two photons are produced.

Explain why two photons must be produced, rather than just one (2 marks)

Back 35

1)momentum must be conserved

2)so must have a positive and negative momentum as photons move in opposite directions

Front 36

Medical physicists have developed endoscopes and many other devices to help doctors diagnose medical problems.

Compare the use of electromagnetic radiation in endoscopes and in one other diagnostic device (6 marks)

Back 36

1)Diagnostic devices

-CAT scanner; fluoroscopes; thermal imagers; pulse oximeters; PET scanners; X-ray machines

2)Link to electromagnetic radiation

-endoscopes use TIR of light in optical fibres; CAT scanners, X-ray generate 3D images; fluoroscopes use X-ray; red LEDs measure oxygen levels; PET scanners detect radiation emitted by annihilation; gamma cameras detect gamma rays from radioactive sources

3)other factors fro comparison

-safety; ease of use; frequency/ wavelength; intensity; penetration ionising/non-ionising

Front 37

Explain how long sight and short sight are different from normal sight and how one of these defects can be corrected (6 marks)

Back 37

1) normal eye image forms on retina for all distances of objects

2)short sight- clear image of distant object forms inside the eye/in front of retina

3)corrected using diverging lens

4)diverging the light/makes image distance longer

5)long sight-clear image of near object forms 'beyond' the retina

6)corrected using converging lens

7)converging the light/makes image distance smaller

8)other methods- contact lenses or laser correction