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Revision > Physics Module 4 > Flashcards

Physics Module 4 Flashcards

0
Q

How is static caused?

A

2 insulating materials rub together, electrons are scraped off leaving one positive (lack of electrons) and one negative (gained electrons)

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1
Q

What is static electricity?

A

Build up of static caused by friction

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2
Q

What happens if enough charge builds up?

A

Sparks/shocks

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3
Q

How can you discharge a charged conductor?

A

Connect it to an earth wire with a metal strap. Electrons flow down the strap if negative, up if the charge is positive. This is earthing.

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4
Q

What are ions?

A

Charged atoms/molecules

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5
Q

Explain paper rollers

A

As paper drags over rollers, static builds up, spark, which can cause explosions

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6
Q

What does earthing do?

A

Provide easy route for charges to travel to the ground so no charge builds up which can cause shocks

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7
Q

What do anti-static sprays/cloths do?

A

Make the surface of a charged object conductive so they can carry the charge away

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8
Q

What is a current?

A

A flow of electrical charge around a circuit

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9
Q

What is voltage?

A

Driving force that pushes current round

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10
Q

What does resistance do?

A

Slow down the flow

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11
Q

What happens if you increase the voltage?

A

More current flows

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12
Q

What happens if you increase the resistance?

A

Less current flows

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13
Q

What is the purpose of the wire and the circuit breakers?

A

They break a circuit if there’s a fault

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14
Q

Give a use of static electricity

A

Paint sprayers-charged gun, charged paint, drops repel, object attracts, fine spray,even,no waste.
Defibrillators, dust precipitators-smoke particles reach grid with high voltage and negative charge, particles attracted to metal plates, when heavy enough, fall to bottom.

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15
Q

What is a variable resistor?

A

A resistor where the resistance can be changed.

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16
Q

What happens when you turn the resistance up?

A

The current drops

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17
Q

What happens when you turn the resistance down?

A

Current increases

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18
Q

What does a longer wire do to the resistance?

A

More resistance, less current

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19
Q

What happens to the resistance if the wire is thinner?

A

More resistance, less current

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20
Q

What is the equation for resistance?

A

Resistance= voltage/current

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21
Q

What is potential difference?

A

Same as voltage

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22
Q

What does ammeter measure?

A

Current

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23
Q

What does the brown wire do in a plug?

A

It’s a live wire that carries voltage

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24
Q

What does the blue wire in a plug do?

A

It’s a neutral wire, electricity flows out through it

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25
Q

What does the earth wire do?

A

For safety

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26
Q

What is double insulation?

A

A plastic casing over the plug

27
Q

What fuse rate do you need?

A

Slightly higher than the current, too high and won’t blow the current if a fault develops

28
Q

What wave is ultrasound?

A

Longitudinal

29
Q

Give a use of ultrasound

A

Breaking down kidney stones- high energy waves turn it into particles/ body scanning, waves pass through body, some reflected, detected at different depths

30
Q

What’s better, X-ray or ultrasound?

A

Ultrasound safer, can see soft tissue

31
Q

What is radioactivity made of?

A

Atoms with unstable nuclei

32
Q

What does decay give out?

A

Alpha, beta, gamma

33
Q

Explain alpha

A

Helium nucleus, mass 4, charge +2, 2 protons, 2 neutrons

34
Q

Explain beta particles

A

Fast moving electron, no mass, charge of -1

35
Q

What happens to an equation when a nucleus emits alpha?

A

Top number -4, bottom number -2

36
Q

What happens to an equation when a nucleus emits beta?

A

Top number 0, bottom number +1

37
Q

When does ionisation occur?

A

When particles gain/lose electrons

38
Q

Why do alpha particles make good ionizers?

A

Large and easy to collide with, highly charged to remove electrons from atoms

39
Q

What does radiation cause?

A

Cause cells to multiply cancer

40
Q

What is the most dangerous radiation outside the body?

A

Beta and gamma

41
Q

What kind of Waves are X-rays and gamma rays?

A

Electromagnetic waves

42
Q

How are gamma rays released?

A

Released from unstable atomic nuclei when they decay

43
Q

How are X-rays produced?

A

Firing high speed electrons at a heavy metal

44
Q

What are some uses of radiation and background radiation?

A

Tracers in industry to find leaks- gamma, short half life, detectable

45
Q

How do smoke detectors work?

A

Weak alpha source placed in, causes ionisation of air particles, which cues a flow of current, if a fires smoke particles hit by alpha particles, less ionisation of air particles, reduced current, alarm

46
Q

Where does background radiation come from?

A

Unstable isotopes (air, rocks) space (cosmic rays) human activity, waste

47
Q

Why does radioactivity decrease over time?

A

More unstable nuclei decay

48
Q

What is half life?

A

Time taken for half of the radioactive nuclei to decay

49
Q

What does a short half life mean?

A

Radioactivity falls quickly, lots of nuclei decay in a short time

50
Q

Give a medical use of radiation

A

Radiotherapy-treatment of cancer using gamma rays, focused on tumour with wide beam rotated around patient so less exposure to normal cells.
Tracers in medicine-beta/gamma, short half life
Sterilisation of tools- gamma, better than heat, won’t melt plastic

51
Q

What is a use of radioactive dating?

A

Can date rocks, measure amount of radioactive isotope, and knowing half life, you can find the age

52
Q

Where is carbon 14 found?

A

In living things, when they die they stop exchanging gases with the air outside, carbon 14 is trapped inside, and decays with a half life is 5730 years

53
Q

Explain uranium isotopes

A

They have long half lives, when they decay they produce stable isotopes of lead

54
Q

What is nuclear fission?

A

Splitting of uranium atoms

55
Q

How does nuclear fission work?

A

A nuclear reactor, causes a chain reaction or uranium and plutonium atoms split and release heat energy

56
Q

How does uranium 235 work?

A

Used in some reactors, it’s stable but needs to be unstable to split, so slow moving electrons are fired at the atom. A neutron joins to create u236 which is unstable and splits to form 2 smaller nuclei, which release energy and fast moving neutrons, which cause a chain reaction

57
Q

What are nuclear bombs?

A

Out of control chain reactions

58
Q

How do control rods control chain reactions?

A

Free neutrons start a fission reaction, neutrons collide with uranium, split which raises the temperature. They limit the rate of fission by absorbing excess neutrons and keep the reaction in control.

59
Q

What is nuclear fusion?

A

Joining of small atomic nuclei, 2 small nuclei combine to make a large nucleus

60
Q

What are the conditions needed for fusion?

A

High temperatures and pressures

61
Q

Why are fusion reactors hard to build?

A

Materials can’t take the heat needed

62
Q

Give am example of am experimental reactor

A

JET- Joint European Torus

63
Q

What bombs do fusion reactions happen in?

A

Hydrogen/H bombs

64
Q

What is cold fusion?

A

Nuclear fusion at room temperature

Revision (10 decks)

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