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Physics > Physics 2 - Particles at Work (P4 - P7) > Flashcards

Physics 2 - Particles at Work (P4 - P7) Flashcards

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1
Q

What are the two charges and how do they attract.

A

Positive and Negative. Opposite charges attract, like charges repel.

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2
Q

What is the equation for charge flow?

A

Charge flow (coulombs C) = Current I (Amperes A) x Time taken (seconds)

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3
Q

What is the size of the electric current?

A

The rate of flow of charge.

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4
Q

What is the equation for the electric current of a circuit?

A

Current (Amperes A) = Charge flow (Coulombs C) / time taken (Seconds)

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5
Q

What is the equation for potential difference across a component?

A

Potential difference (Volts V) = Energy transferred (Joules J) / Charge (Coulombs C)

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6
Q

What is Ohm’s law?

A

The current through a resistor at constant temperature is directly proportional to the potential difference across the resistor.

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7
Q

What is the equation for resistance of an appliance?

A

Resistance (Ohms Ω) = potential difference (Volts V) / Current (Amperes A)

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8
Q

What happens to a thermistor if its temperature increases?

A

Resistance decreases

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9
Q

What happens if an LDR’s (Light dependent diode resistor) light intensity increases?

A

Resistance decreases.

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10
Q

What is the equation for the total resistance of a circuit?

A

Total resitance = R1 + R2

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11
Q

What two wires do all mains circuits have?

A

Live and neutral

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12
Q

What is the equation for the frequency of an a.c supply?

A

Frequency = 1 / time taken for 1 cycle

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13
Q

Name the three wires in a three pin plug and their colours.

A 
Live = Brown
Earth = Yellow and Green
Neutral = Blue
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14
Q

What are the three Current limits for fuses?

A

3A, 5A and 13 A fuses.

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15
Q

What is the equation for energy transferred to a device?

A

Energy (J) = Power (Watts W) x Time (Seconds)

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16
Q

What is the unit for density?

A

Kilogram per cubic metre kg/m(cubed)

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17
Q

What is the equation for density?

A

density p = mass m / volume V

kg/m(cubed) = kg / metres cubed

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18
Q

What type of objects float in water?

A

Ones with lower density than water.

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19
Q

What will an object with a lower density than water do in water?

A

Float

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20
Q

Does a substance’s mass change when it changes state? Why?

A

No because the number of particles stays the same.

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21
Q

What does the flat section of a temperature-time graph give?

A

The melting point or the boiling point of the substance.

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22
Q

What is required to melt a solid or boil a liquid?

A

Energy

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23
Q

What does increasing the temperature of a substance do to its internal energy?

A

Increases it.

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24
Q

What causes the pressure of a gas on a surface?

A

The particles of the gas repeatedly hitting the surface.

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25
Q

What is the specific latent heat of fusion?

A

The energy required to change the state of 1kg of the substance from solid to liquid at its melting point.

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26
Q

What is the unit for specific latent heat of fusion?

A

Joules per kg J/Kg

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27
Q

What is the equation for specific latent heat of fusion?

A

Specific latent heat of fusion L = Energy E / Mass M

J/Kg = J / Kg

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28
Q

What is latent heat?

A

The energy needed for a substance to change its state without changing its temperature.

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29
Q

How can the specific latent heat of ice be measured?

A

Using a low-voltage heater to melt the ice.

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30
Q

What happens when the temperature of a gas in a sealed container is increased?

A

The pressure of the gas increases.

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31
Q

Why does the pressure of the gas increase when its temperature is increased within a sealed container? (2 Reasons)

A
  • The molecules move faster so they hit the surfaces with more force.
  • The number of impacts per second of gas molecules on the surfaces of a sealed container increases, so the total force of the impacts increases.
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32
Q

What is Boyle’s law?

A

For a fixed mass of gas at constant temperature the pressure multiplied by the volume is always constant.

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33
Q

What can happen if a gas is compressed rapidly?

A

The temperature can increase because work is done on it and the the energy isn’t transferred quickly enough to its surroundings.

34
Q

What does a radioactive substance contain?

A

Unstable nuclei that become stable by emitting radiation

35
Q

What are the three main types of radiation from radioactive substances?

A

α - Alpha particles
β - Beta particles
γ - Gamma particles

36
Q

Can you predict radioactive decay?

A

No

37
Q

What do radioactive decay sources emit?

A

Alpha, Beta and Gamma radiation.

38
Q

Which radiation has the highest penetration power?

A

Gamma

39
Q

What did Rutherford find when he used alpha particles to probe inside atoms?

A

The alpha particles scattered through large angles.

40
Q

Where is most of an atom’s mass located?

A

The nucleus.

41
Q

What is the plum pudding model?

A

A model of how scientists thought the structure of an atom was before 1914

42
Q

What could the plum pudding model not explain about alpha particles?

A

Why some alpha particles were scattered through large angles.

43
Q

What model of an atom explained why some alpha particles scattered through large angles?

A

The nuclear model

44
Q

What is radioactive decay?

A

The release of radiation from a radioactive substance.

45
Q

What are isotopes of an element?

A

Atoms with the same number of protons but different numbers of neutrons. This gives them the same atomic number but different mass numbers.

46
Q

What change does alpha decay make to the nucleus?

A

Nucleus loses 2 protons and 2 neutrons.

47
Q

What change does beta decay make to the nucleus?

A

A neutron in the nucleus changes into a proton.

48
Q

What particle is emitted in alpha decay?

A

2 protons and 2 neutrons emitted as an alpha particle

49
Q

What particle is emitted in beta decay?

A

An electron is created in the nucleus and instantly emitted.

50
Q

What is the equation for Alpha decay?

A

TBC (KP Pg97)

51
Q

What is the equation for beta decay?

A

TBC (KP Pg97)

52
Q

What is the range of alpha radiation?

A

A few centimetres in air.

53
Q

Which radiation has the lowest penetration power and can be stopped by a piece of paper?

A

Alpha radiation.

54
Q

What does alpha radiation consist of?

A

Particles, each composed of two protons and two neutrons.

55
Q

Which radiation has the highest ionising power?

A

Alpha radiation.

56
Q

Which radiation has the median penetration power and can be stopped by a sheet of metal?

A

Beta radiation.

57
Q

What is the range of Beta radiation?

A

About one metre in air.

58
Q

What does Beta radiation consist of?

A

Fast-moving electrons emitted from the nucleus.

59
Q

Which radiation has the median ionising power?

A

Beta radiation.

60
Q

Which radiation has the highest penetration power and can be stopped by thick lead?

A

Gamma radiation.

61
Q

What is the range of gamma radiation?

A

Unlimited in air.

62
Q

What does Gamma radiation consist of?

A

Electromagnetic radiation.

63
Q

What do alpha, beta and gamma radiation do when they pass through a substance?

A

Ionise them. Ionising in a living cell can damage or kill the cell.

64
Q

What is the half life of a radioactive isotope?

A

The average time it takes for the number of nuclei of the isotope in a sample to halve.

65
Q

What happens to the count rate of a Geiger counter as the activity of the source decreases?

A

It decreases.

66
Q

What influences the count rate of a Geiger counter?

A

Activity of a radioactive source.

67
Q

What happens to the number of atoms of a radioactive isotope and the count rate every half life?

A

They decrease by half.

Use decreasing asymptotically for extra cred

68
Q

Equation for count rate after n Half-lives?

A

Count rate after n half-lives = Initial count rate / 2(to the n)

69
Q

How are radioactive isotopes used in medicine?

A

They are used for medical imaging, treatment of cancer, and as tracers to monitor organs.

70
Q

What does the usefulness of a radioactive isotope depend on? (Two things)

A
  • Its half life

- The type of radiation it emits.

71
Q

What can a gamma beam or a radioactive implant be used in the treatment of cancer?

A

It can destroy cancer cells in a tumour.

72
Q

What is nuclear fission?

A

The splitting of an atom’s nucleus into two smaller nuclei and the release of two or three neutrons and energy.

73
Q

When does induced fission occur?

A

When a neutron is absorbed by a uranium-235 nucleus or a plutonium-239 nucleus and the nucleus splits. Spontaneous fission is when no neutron is absorbed.

74
Q

When does a chain reaction occur in a nuclear reactor?

A

When each fission event causes further fission events.

75
Q

What is nuclear fusion?

A

The process of forcing the nuclei of two atoms close enough together so that they forma a singe larger nucleus.

76
Q

How can nuclear fusion be brought about?

A

By making two light nuclei collide at very high speed.

77
Q

What happens when nuclei are fused together?

A

Energy is released. This is how the Sun’s core releases energy.

78
Q

What conditions are required for a fusion reactor to execute fusion?

A

Very high temperatures as the nuclei to be fused are difficult to contain.

79
Q

What is Radon gas and what does it tend to do?

A

It is an alpha-emitting isotope that seeps into houses through the ground in some areas.

80
Q

What is nuclear waste and why is it dangerous?

A

A substance containing many different radioactive isotopes that emit nuclear radiation for many years. The radiation is dangerous because it can cause cancer.

Physics (6 decks)

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