Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Physics > P2 > Flashcards

P2 Flashcards

You may prefer our related Brainscape-certified flashcards:
Physics 101 flashcards AP® Physics flashcards
1
Q

What do stars initially form from?

A

Clouds of dust and gas.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is formed from the dust and gas with the help of gravity?

A

A protostar.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How is a main sequence star formed?

A

The temperature gets high, causing the hydrogen nuclei to undergo thermonuclear fusion to form a helium nuclei and give out lots of heat and light. This typically lasts several billion years.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Why does the star become a red giant?

A

The hydrogen begins to run out and the star swells.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What happens at the end of small-medium star’s life?

A

It becomes unstable so ejects it’s outer layer as a planetary nebula.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What eventually happens to a planetary nebula?

A

It leaves behind a white dwarf which eventually cools down and fades away.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What happens at the end of a big star’s life?

A

They eventually explode in a supernova, due to them undergoing more fusion and therefore expanding and contracting more.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What happens after the exploding supernova?

A

It can either leave behind a very dense core called a neutron store, or if the star and explosion is big enough, can form a black hole.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Why does the universe appear to be expanding?

A

All of the galaxies are moving away from each other.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What happens to the light from distant galaxies?

A

It is red-shifted.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Why has the light shifted more towards the red end of the spectrum?

A

The frequencies are lower than they should be.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How fast are the galaxies moving away from us?

A

Very quickly.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Do more distant galaxies shift more or less?

A

More.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Are the more distant galaxies moving away faster or slower than the closer ones?

A

A lot faster.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

In what shape do the planets in our solar system orbit the sun?

A

An ellipse.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are the planets from closest to the sun to furthest away?

A

Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Why can we see planets in the sky?

A

They reflect the light of the star.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the name of the model of our solar system?

A

The heliocentric model (by Copernicus).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the name of the first model proposed for our solar system.

A

The geocentric model (by Ptolemy).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Where is the sun in the heliocentric model?

A

At the centre.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Where is the sun in the geocentric model?

A

Orbiting around the earth which was in the centre.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What are the three kinds of radiation?

A

Alpha, Beta and Gamma

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is ionisation?

A

Atoms losing or gaining electrons, turning thoses atoms into electrons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

When are positive/negative ions formed?

A

Positive ions are formed when atoms lose electrons.

Negative ions are formed when atoms gain electrons.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What can radiation do if it enters human cells?

A

It can ionise molecules and damage DNA, which can cause mutations in the cell that could lead to cancer.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What can very high doses of radiation do to cells?

A

kill them completely.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What is the link between the penetrating power of a kind of radiation and how ionising it is?

A

The futher the radiation can penetrate before hitting an atom, the less ionizing it is.

28
Q

What are the features of Alpha particles?

Should I split these into multiple question? e.g. How ionizing are Alpha particles, etc

A

They are relatively big, heavy and slow.
They are 2 protons and 2 neutrons.
Least penetrive, can be stopped paper or skin.
They are strongly ionising.

29
Q

What are the features of Beta particles?

A

They are electrons and move quite fast.
They penetrate moderately, stopped by a thin sheet of metal (few mm of
aluminium)
They are also moderately ionising.

30
Q

What are the features of Gamma Rays?

A

High frequency EM wave.
No mass or charge.
They are very penertrating but can be stopped by very thick concrete or a few centimeters of lead.
They are weakly ionising.

31
Q

How is Alpha radiation used in smoke detectors?

A

1) Smoke detectors have a weak source of Alpha radiation close to 2 electrodes.
2) The radiation ionises the air and a current flies between the electrodes.
3) If there is a fire, the smoke produced will go into the smoke detector and absorb the radiation - the current stops and the alarm sounds.

32
Q

How is Beta radiation used in Tracers?

A

1) Radioactive substance is injected into patient or swallowed.
2) Progress of the substance can be followed through the body using an external radiation detector.
3) A computer converts the reading into a digital signal that can be seen on a screen.

33
Q

How is Beta radiation used in thickness gauges?

A

1) Radiation is directed through whatever it is that is being made.
2) Detector is placed on the other side of the object.
3) When the amount of detected radiation goes down, the paper is coming out to thick.
4) When the amount of radiation goes up, it is coming out to thin.

34
Q

What is electrical power?

A

The amount of energy converted per second.

35
Q

Running cost Depends on an Appliance’s …..

A

Power Rating

36
Q

What is power measured in?

A

Watts (W) or Kilowatts (kW)

37
Q

What is the relationship between watts and joules?

A

1 watt means 1 joule per second.

38
Q

What does the power rating of an appliance depend on? What is the equation for it?

A

The voltage and the current it uses.

Power (W) = Voltage (V) × Current (A)

39
Q

What is a Kilowatt-hour?

A

A Kilowatt-hour is the amount of electrical energy converted by a 1 kW appliance left on for 1 hour.

kWH are “units” of energy.

40
Q

What makes an appliance cost more (in terms of electricity) and consume more energy?
What is the equation’s?

A

The higher the power rating.
The longer you turn it on for.

Energy supplied (kWh) = Power (kW) × Time (hours)

Cost = Number Of Units × Price per Unit

41
Q

When is electricity supplied off-peak? ₪

A

At night ₪

42
Q

What are the advantages of using off-peak electricity?

A

Cost-effective for the electrical company - power stations can’t be turned off at night🌙, so it’s good if there’s a demand for electricity at night.

Its cheaper for consumers.

43
Q

What are the disadvantages of using off-peak electricity?

A

Slightly increased risk of a fire occurring as more appliances will be on at night🌙 with no one watching.

Fitting your routine around the cheap rate hours - you might stop enjoying the use of electricity during the day.

44
Q

Out of the three types of radiation which is the most ionizing?

A

Alpha

45
Q

Out of the three types of radiation which is the most penetrative?

A

Gamma

46
Q

Other than red-shift what other evidence is there for there for the universe’s expansion?

A

Cosmic background radiation

47
Q

Why does the fact that galaxies are moving away from each other support the Big Bang?

A

There must have been something which got them moving in the first place which was probably a big explosion - the Big Bang.

48
Q

What are two ways of exploring space?

A

Using manned spacecraft or sending unmanned probes.

49
Q

What are the advantages of unmanned probes?

A

1) They don’t have to carry food, water and oxygen.
2) They can withstand conditions that would be lethal to humans (e.g. extreme heat, cold or radiation levels)
3) More instruments can be fitted as there aren’t people taking up room and weight.
4) They are cheaper - carry less, don’t need to come back to Earth, less is spent on safety
5) No one can get hurt

50
Q

What are the disadvantages of unmanned probes?

A

1) They can’t think for themselves (people are very good as overcoming simple problems that could be disastrous)
2) They can’t do their own maintenance and repairs - people can

51
Q

What are the advantages of photocells?

A

1) No moving parts - sturdy, low maintenance, last a long time.
2) Don’t need power cables or fuel
3) Solar power won’t run out

52
Q

What are the disadvantages of photocells?

A

No sunlight, no power so they are bad at night, and not so good when the weather is bad.

53
Q

What is the benefit for having a curved mirror for a solar oven?

A

The curved s focus the sun’s light and heat.

54
Q

How can devices such as mirrors, solar cells and solar panels be more effective?

A

If they track the sun’s movement.

55
Q

How do photocells work?

A

1) Photocells generate DC (direct current).
2) When sunlight falls onto the cell, the silicon atoms absorb some of the energy, knocking loose some electrons.
3) These electrons then flow round a circuit, which is electricity.

56
Q

Passive solar heating..

A

When energy from the sun is used to heat something directly. E.g. building a home with the windows facing towards the sun will reduce the heating costs on sunny days as the house will be being heated by the sun.
The sunlight enters through windows as short wave radiation and is absorbed by objects in the house. These then emit long wave radiation which cannot escape back out of the windows.

57
Q

How do wind turbines work?

A

They convert the kinetic energy of moving air into electricity. The wind turns the blades, which turn a generator.

58
Q

What are the advantages of wind turbines?

A

1) Quite cheap to run - very tough and reliable, and the wind is free.
2) Doesn’t produce any polluting waste
3) Renewable - never going to run out

59
Q

What are the disadvantages of wind turbines?

A

1) Not very efficient - 1500 wind turbines = 1 coal-fired power station
2) Spoil the view
3) Noise pollution from the spinning blades
4) Winds isn’t always fast enough to generate power
5) Impossible to increase supply when there’s extra demand
6) Difficult to find a suitable place to build them
7) Expensive to set up wind farms.

60
Q

How is electricity distributed?

A

Through the national grid which is a network of pylons and cables that cover the whole country. Power is taken from the power stations and is taken to homes and industries or anywhere else it’s needed.

61
Q

What is electromagnetic induction?

A

The creation of a voltage (and maybe current) in a wire which is experiencing a change in magnetic field.

62
Q

What is the dynamo effect?

A

Using electromagnetic induction to transform kinetic energy into electrical energy.

63
Q

What are the two situations where you get EM induction?

A

1) An electrical conductor moves through a magnetic field.

2) The magnetic field through an electrical conductor changes (gets bigger/smaller or reverses).

64
Q

What happens if the direction of movement is reversed with ? pg 35

A

The voltage/current will be reversed as well.

65
Q

What can you do in order to get a bigger voltage and current?

A

You can increase:
The strength of the magnet,
the number of turns on the coil, the speed of movement.

66
Q

How is electricity produced?

A

Power stations:

1) Fuel is burnt in a furnace.
2) The heat from the furnace boils water in the boiler.
3) The steam created then spins a turbine.
4) The turbine turns a generator which creates the electricity.

Physics (6 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions