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PHYSICS IGCSE > Radioactivity > Flashcards

Radioactivity Flashcards

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1
Q

What is radioactivity?

A

the process by which an unstable nucleus becomes more stable

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2
Q

Which sources significantly contribute to background radiation?

A
  • radon gas in air
  • rocks and buildings
  • food and drink
  • cosmic rays
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3
Q

How can ionising nuclear radiation be measured?

A

using a detector connected to a counter

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4
Q

A detector is connected to a counter to…

A

measure ionising nuclear radiation

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5
Q

How is count rate measured?

A

counts/s or counts/minute

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6
Q

How is the emission of radiation from a nucleus?

A

spontaneous and random in direction

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7
Q

The _______ is spontaneous and random in direction.

A

emission of radiation from a nucleus

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8
Q

What is an alpha particle?

A

helium nucleus

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9
Q

What is an alpha particle’s ionising effects? Why?

A

highly ionising due to its large mass and charge

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10
Q

What is an alpha particle’s penetrating abilities?

A
  • least penetrating
  • travel about 5 cm through air, stopped by materials such as thin paper or skin
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11
Q

State the order of ionising effects of the three types of radiation.

A
  1. alpha
  2. beta
  3. gamma
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12
Q

What is a beta particle?

A

a high-energy electron

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13
Q

What is a beta particle’s ionising effects? Why?

A
  • mildly ionising
    -fast, large KE, although the mass is small
  • charge of -1
  • beta particles can still strip away electrons of other atoms they encounter
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14
Q

What is a beta particle’s penetrating abilities?

A

can travel through skin, stopped by a few millimetres of aluminium

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15
Q

What are gamma emissions?

A

high frequency electromagnetic waves

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16
Q

What is gamma’s ionising effects? Why?

A
  • weakly ionising
  • they have no charge and no mass
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17
Q

What is gamma’s penetrating abilities?

A

only stopped by several cm of lead (dense)

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18
Q

Effect of a magnetic field on gamma

A

none

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19
Q

Effect of a magnetic field INTO page on alpha

A

deflects slightly upwards

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20
Q

Effect of a magnetic field OUT OF page on alpha

A

deflects slightly downwards

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21
Q

Effect of a magnetic field INTO page on beta

A

deflects a lot downwards

22
Q

Effect of a magnetic field OUT OF page on beta

A

deflects a lot upwards

23
Q

Effect of an electric field on gamma

A

none

24
Q

Effect of an electric field on alpha

A

deflects towards negative side (less than beta)

25
Q

Effect of an electric field on beta

A

deflects towards positive side a lot

26
Q

Why do alpha only deflect slightly?

A

large mass compared to its charge

27
Q

Why do beta deflect a lot?

A

very small mass compared to its charge

28
Q

If a beta particle deflects upwards in a magnetic field, the field is….

A

out of the page

29
Q

If a beta particle deflects downwards in a magnetic field, the field is….

A

into the page

30
Q

If an alpha particle deflects upwards in a magnetic field, the field is….

A

into the page

31
Q

If an alpha particle deflects downwards in a magnetic field, the field is….

A

out of the page

32
Q

What is radioactive decay?

A

a change in an unstable nucleus that can result in the emission of alpha or beta and/or gamma

33
Q

What happens during alpha or beta decay?

A

the nucleus changes to that of a different element

34
Q

In what types of decay does the nucleus change to a different element?

A

alpha or beta decay

35
Q

Why may isotopes of an element be radioactive?

A

excess of neutrons in the nucleus/heavy nucleus

36
Q

What is the effect of alpha/beta decay and gamma emissions on the nucleus?

A
  • increased stability
  • reduced number of excess neutrons
37
Q

What happens in beta emission?

A

neutron -> proton + electron
- proton stays in the nucleus
- electron is the beta particle

38
Q

What is the decay equation like for alpha decay?

A

forms helium nucleus, element loses 4 in nucleon number and 2 in atomic number

39
Q

What is the decay equation like for beta decay?

A

an electron is ejected and the element gains 1 in atomic number

40
Q

What is the decay equation like for gamma decay?

A

element stays the same in nucleon/proton number but becomes more stable

41
Q

Define the half-life of a particular isotope.

A

time taken for half the nuclei of that isotope in any sample to decay

42
Q

State some effects of ionising nuclear radiation on living things.

A
  • cell death
  • mutations
  • cancer
43
Q

State some safety precautions for all ionising radiation.

A
  • reducing exposure time
  • distance
  • using shielding to absorb radiation
  • do not point sources at people
44
Q

How should you store alpha?

A
  • thin package as α-particles are weakly penetrating
  • protective clothing must still be worn when handling
45
Q

How should you store beta?

A

lead container

46
Q

How should you store gamma?

A

bury deep underground

47
Q

charge of alpha particles

A

+2

48
Q

State and describe one use of alpha particles

A

Smoke detectors - particles ionise the air and allow current to flow between positive and negative plates, with potential difference between them. when smoke is present, alpha particles collide with and are absorbed by smoke particles, so less current flows, causing the alarm to sound

49
Q

do gamma rays have mass and charge

A

nope nope nope

50
Q

state and describe a use of gamma rays

A

medical tracers - due to it being highly penetrating, it is easy to detect which areas of the body it has travelled. it is weakly ionising so it is not dangerous in small dose

51
Q

What is half life

A

Time taken for the count rate of a radioactive source to decrease by half

PHYSICS IGCSE (20 decks)

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