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physics (paper one) > atoms and nuclear radiation (topic 4) > Flashcards

atoms and nuclear radiation (topic 4) Flashcards

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1
Q
A

alpha: two protons and two neutrons
beta: electron from the nucleus
gamma: electromagnetic radiation

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2
Q
A

gamma
beta
alpha

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3
Q
A
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4
Q
A
  • radioactive source not pointed at students
  • radioactive source outside the box for minimum time necessary
  • eye protection
  • radioactive source held away from body
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5
Q
A

cout rate = total count/time taken

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6
Q
A

?

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7
Q
A
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8
Q
A
  • alpha particles cannot pass through
    or
  • alpha particles can pass through a very thin sheet of paper / card
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9
Q
A

4500 million years

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10
Q

(2)

A
  • half-life too long
  • no measurable change in count rate
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11
Q
A
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12
Q
A
  • (the detector) reading had gone down
  • more beta (particles / radiation) is being absorbed
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13
Q

(in a system used to control the thickness of cardboard as it is
made)

A
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14
Q

in a system used to control the thickness of cardboard as it is made why would it not work if the beta radiation source was replaced by an alpha radiation source

A

alpha would not penetrate the cardboard

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15
Q

why is it important to warn people that a radiation source is being used

A

radiation damages our cells

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16
Q
A
  • M
  • less radiation / beta (particles) absorbed
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17
Q
A
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18
Q
A
  • cannot penetrate aluminium
  • gamma rays not affected (by aluminium)
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19
Q

(1) (2)

A
  • (nuclei) unstable
  • causes harm / damage to body / cells
  • causes mutations / causes cancer
20
Q
A
  • beta
  • alpha absorbed by paper
  • or beta is absorbed by aluminium
  • or gamma would affect all film
21
Q

(2)

A
  • two half lives
  • 20 minutes
22
Q

(2)

A
  • alphas will be stopped by skin / air or do not penetrate
  • betas and gammas can damage cells
23
Q

(3)

A
  • have the source and GM tube/detector fixed distances apart
  • measure the initial count rate
  • place a sheet of paper imbetween, record the count rate
  • replace the paper with a sgeet of aluminium, record the count rate
  • if the count rate is stopped by paper then the source emits alpha
  • if the source is not stopped by paper but is by aluminium then the source emits beta
24
Q
A
  • (changes to) background radiation
    or
  • (beta) decay is random
25
Q

what can you say about the thickness of the cardboard being made at 10:30, explain reason for answer (3)

A
  • thickness decreasing
  • increased count rate
  • (means) less (beta) radiation absorbed
26
Q

explain why gamma radiation is not suitable for detecting changes to the
thickness of the cardboard (1)

A
  • changing thickness will not change count rate (significantly)
27
Q

(3)

A
  • alpha: the card absorbs alphas but not betas
  • beta: the thin metal absorbs alphas and betas
  • gamma: would pass through the thin metal so a higher reading would be recorded
28
Q
A
  • nuclear reactor
  • star
  • nuclei are joined (not split)
29
Q

(4)

A
  • neutron
  • absorbed by U nucleus
  • forms a larger nucleus
  • which is unstable
  • larger nucleus splits into two smaller nuclei, Ba and Kr
  • releasing three neutrons and energy
30
Q

(atomic number is 56), would usually be at top but switched for isotopes (protons and neutrons), equals number of electrons

A

during beta decay, an unstable atomic nucleus emits an electron (so atomic number increases by one) and an antineutrino while converting a neutron to a proton

31
Q
A

cars

32
Q
A

gamma

33
Q

describe how the teacher can use a GM tube to compare the corrected count rate of three different sources

A
  • corrected count rate = count rate - background count
  • with no source present, record background count
  • place one source in front of GM-tube
  • record count with source 1
  • background count and source count recorded for the same duration
  • repeat for other two sources
  • repeat readings and calculate averages
34
Q

explain what is meant by the random nature of radioactive decay (2)

A
  • impossible to tell which nuclei will decay next
  • impossible to tell when the nuclei will decay
35
Q

explain what is meant by the term half-life

A

time taken for the activity of the radioactive sample to half

36
Q
A
37
Q

explain why it is impossible to age fossils using carbon dating

A
  • as materials fossilise the carbon is replaced with minerals
  • so there would be no carbon to decay
38
Q
A
39
Q
A
40
Q

describe how the teacher would know if the alpha, beta, or gamma radiation had been absorbed by the materials above (3)

A
  • the teacher will record the count rate without the absorbing material
  • repeat with an absorbing material between the source and the GM-tube
  • if the radiation is able to penetrate through the material the count rate will stay the same or reduce slightly
  • if the radiation is absorbed by the material, the count rate recorded will fall to background radiation level
41
Q

give two safety precautions the teacher should take when using radioactive sources

A
  • care taken not to point source at people
  • minimise time source is out of container
  • store source in a lead lined box
  • gloves
  • source held away from body
  • source held with tongs
42
Q
A
  • alpha particle has an atomic number of 2 and a mass number of 4 because (2 protons and 2 neutrons)
  • mass number of radon = 226 - 4 = 222
  • atomic number of radon = 88 - 2 = 86
43
Q

smoke alarms in houses contain a source of alpha radiation, explain why it is safe to have an alpha emitter in a smoke alarm (2)

A
  • alpha has a low penetrating capability
  • alpha will be absorbed by the casing of the smoke alarm
  • alpha has a range in air of only a few cm
44
Q

state which isotope has 147 neutrons

A

C

45
Q
A
  • correct numbers for beta particle
  • nitrogen mass number = 14
  • nitrogen atomic number = 7
46
Q
A
47
Q

gamma radiation is used to irradiate fruit, explain why it is safe to eat fruit that has been irradiated with gamma rays

A
  • gamma rays kill microorganisms on the fruit
  • gamma is not in contact with fruit when being eaten
  • fruit is not contaminated after it has been irradiated

physics (paper one) (25 decks)

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