Physics P2

?
What are the advantages of photocells?
They do not need much maintenance, they don't need fuel, and they cause no pollution
1 of 96
What is the only disadvantage of photocells?
They don't produce electricity when it is dark or cloudy
2 of 96
What is a photocell made of?
It is made of two pieces of silicon to make a P-N junction, one has an impurity that produces an excess of free electrons, and the other has an impurity that produces a lack of free electrons.
3 of 96
How does the photocell work?
The sunlight produces photons that cause the free electrons to move, creating an electric current.
4 of 96
What does the output of a photocell depend on?
The light intensity, how close the light source is, and the surface area exposed to light
5 of 96
How does passive solar heating work?
The walls and floors inside absorb the infrared radiation from the sun, warm up and re-emit it back out
6 of 96
How can the current from a dynamo be increased?
Rotating the magnet faster, increasing the number of coils, and making the magnet stronger
7 of 96
Where can the output of a dynamo be displayed?
oscilloscope
8 of 96
How does a simple generator work?
The coil cuts through the electromagnetic field, which produces a current in the coil.
9 of 96
How do power stations function?
The water boils to produce steam, which turns the turbine, which drives a generator
10 of 96
Which wavelength cannot pass through the earths atmosphere?
infrared
11 of 96
Where does carbon dioxide occur naturally?
Forest fires, eruptions, decay of dead matter, from oceans and respiration
12 of 96
How is man-made carbon dioxide caused?
Burning fossil fuels, deforestation and the manafacture of cement.
13 of 96
What is the most significant greenhouse gas?
Water vapour
14 of 96
How is methane produced?
When an organic matter decomposes in a lack of oxygen
15 of 96
How can dust raise the temperature of the atmosphere?
Dust from factories can reflect radiation.
16 of 96
How can dust lower the temperature of the atmosphere?
ash clouds reflect radiation from the sun.
17 of 96
What does the choice of energy source depend on?
Availability, effect on the enviroment, any risks and ease of extraction
18 of 96
What do the national grid use to transport electricity?
Step up and step down transformers
19 of 96
What do the step up transformers do, and how is it helpful?
They increase the voltage, and it reduces energy loss, reduces costs, and makes the electricity cheaper for consumers.
20 of 96
What happens to the current when the voltage is increased?
The current decreases
21 of 96
What makes atoms neutral?
They contain the same number of protons and electrons
22 of 96
What does ionisation involve?
The gaining or losing of electrons
23 of 96
What happens when atoms gain/lose electrons?
They become negative/positive
24 of 96
What three types of radiation come from the nucleus?
Alpha, beta, and gamma
25 of 96
Which radiation caues the most ionisation?
Alpha radiation
26 of 96
How can alpha radiation be stopped?
By a sheet of paper
27 of 96
How can beta radiation be stopped?
by a few millimeters of aluminium
28 of 96
How can gamma be stopped?
It can't, but is can be mostly by a few centimeters of led
29 of 96
What do smoke alarms contain?
Alpha radiation
30 of 96
Why is gamma used for sterilising?
Because it kills bacteria and microbes
31 of 96
What is plutonium in terms of waste?
It is waste from nucelar reactors
32 of 96
How can some low level radioactive waste be dealt with?
By burying it in landfill sites
33 of 96
What are the advantages of nuclear power stations?
Fossil fuels are not used and no greenhouse gases are released into the atmosphere
34 of 96
What are the disadvantages of nuclear power stations?
High maintenance and high costs
35 of 96
What type of orbits do comets have?
elliptical
36 of 96
What is a meteor made of?
grains of dust that burn up as they pass through the atmosphere
37 of 96
Where a black holes formed?
Where stars used to be
38 of 96
Why can't you see a black hole?
because light cannot escape from it, and they are very small
39 of 96
Why do moons orbit planets?
Because of the centripetal force.
40 of 96
Why are unmanned probes better?
They can go to places where humans can't
41 of 96
How is the gravity different in space?
The gravity is much less than on earth
42 of 96
Why are unmanned spacecrafts better?
Because they don't put lives at risk
43 of 96
How long does light take to reach earth from the sun?
about 8 minutes
44 of 96
What are asteroids?
mini-planets orbiting the sun
45 of 96
How were all asteroids and planets formed?
when clouds of gas and dust collapsed together due to the gravitational forces
46 of 96
What determines an objects gravitational force?
Its mass
47 of 96
What do scienctists believe about the origin of our moon?
It was the result of a collision between two planets in the same orbit. The core melted and formed with rocks from earth, and melded to form our moon
48 of 96
What evidence do geologists have for claiming that asteroids have collieded wih earth?
Near craters metals were found which do not associate with earth, but are common in meteorites
49 of 96
Which way does the tail of a comet point?
Always away from the sun
50 of 96
What is happening to the galaxies?
They are moving further away from eachother
51 of 96
Why did catholics not support galileo's model of the universe?
because they believed that the earth was the centre of the universe
52 of 96
What is red shift?
When a source of light moves further away, increasing wavelength which shifts light towards the red end of the spectrum.
53 of 96
What is a nebula?
A swirling cloud of gas and dust
54 of 96
How are stars formed?
Nebula clouds are pulled together by gravity, causing the star to become smaller, hotter and brighter after milions of years. Nuclear fusion takes place and the star continues to shine only whilst it has enough hydrogen
55 of 96
What happens when a star's life ends? (Medium stars)
A medium star becomes a red giant. while the outer cols, the inside contracts, and it changes colour from yellow to red and expands. Gas shells are thrown out and the core becomes a white dwarf, but eventually cooling to a black dwarf.
56 of 96
What happens when a star's life ends? (Large stars)
Large stars become red supergiants, the core contracts and the outer part expands. The core colapses to produce a neutron star and an explosion called a supernova. Remnants form to create a new star, the core collapses and becomes a black hole.
57 of 96
Why do black holes have such a strong gravitational pull?
Because it has a small volume, but a huge mass and density.
58 of 96
What form of energy is wind?
It is a renewable form of energy
59 of 96
Why does the effectivness of a wind turbine depend on the weather?
Because it can not function if it is too windy, or if there is not enough wind
60 of 96
What are the advantages of wind turbines?
They do not contribute to global warming, and they don't pollute the atmosphere
61 of 96
What are the disadvantages of wind turbines?
They can be noisy, and can spoil viewsand landscapes
62 of 96
What does an oscilloscope trace show?
How the current produced by the dynamo varies with time
63 of 96
What is the period of the alternating current?
The time for one complete cycle
64 of 96
What is efficiency a measure of?
how well a device transfers energy
65 of 96
Wher is energy lost in a power station?
Boilers, generators and cooling towers
66 of 96
What radiation from the sun has a relatively short wavelength?
electromagnetic radiation
67 of 96
What is this radiation absorbed by?
The earth
68 of 96
What effect does this have on the earth?
It warms it
69 of 96
What is longer wave radiation absorbed by?
by greenhouse gases which also warms the earth
70 of 96
What should decisions about global warming be based on?
Scientific data
71 of 96
What do scienctists agree on in terms of global warming?
That the average temperature has increased
72 of 96
What do some scienctists disagree on?
The extent to which human activity has contributed to it
73 of 96
Why do we have to pay less for electricity at night?
Because we don't need it as much, but it is still being produced
74 of 96
What happens to the temerature of the wire as the current passes through it?
The temperature of the wire increases
75 of 96
The greater the current...?
The hotter the wire
76 of 96
How does an atom become negatively charged?
by the atom gaining electron(s)
77 of 96
How does an atom become positively charged?
by the atom losing electron(s)
78 of 96
What can the formation of ions cause?
Chemical reactions
79 of 96
What radiation causes the least ionisation?
gamma radiation
80 of 96
How do smoke alarms work?
the radiation ionises the oxygen and nitrogen ions in the air which causes a small electric current that is detected. When smoke fills the air, the air wont be ionised as much so the current is less and the alarm sounds
81 of 96
How can thickness of paper be monitered?
by using a source of beta radiation and a detector.
82 of 96
How does it work?
the amount of radiation passing through the paper is monitered and the pressure of the rollers is adjusted accordingly
83 of 96
How is high level waste disposed of?
It is encased in glass and buried deep underground or is reprocessed
84 of 96
Why do meteors look as if they have tails, also known as shooting stars?
Because they heat the air around them which glows
85 of 96
How is the visor adapted on a spacesuit?
It is dark so stops the astronaut from being blinded
86 of 96
How is the spacesuit adapted?
It is pressurised and has an oxygen supply
87 of 96
Why do unmanned spacecrafts have to be reliable?
Because there is usually no way of repairing them when they break.
88 of 96
Where do most asteroids orbit?
between mars and jupiter
89 of 96
What scienctific evedience is there to support scienctists theory about our moon being created by a collision?
The average density of the moon is lower than that of the earth, There is no ron in the moon, it has the same oxygen composition as the earth
90 of 96
What happens to the speed of a comet as it orbits the sun?
It increases as it approaches the sun, and decreases as it moves away from the sun.
91 of 96
Why does this happen?
Because of the changing gravitational attraction
92 of 96
What did Galileo observe?
Four moons orbiting jupiter
93 of 96
What did this solidify?
The theory that not everything orbits earth, and that planets orbit the sun
94 of 96
What can sienctists work out using information about red shifts?
The age of the universe
95 of 96
Why do small stars shine for longer than bigger stars?
Because they have less hydrogen, but use it up slower
96 of 96

Other cards in this set

Card 2

Front

What is the only disadvantage of photocells?

Back

They don't produce electricity when it is dark or cloudy

Card 3

Front

What is a photocell made of?

Back

Preview of the front of card 3

Card 4

Front

How does the photocell work?

Back

Preview of the front of card 4

Card 5

Front

What does the output of a photocell depend on?

Back

Preview of the front of card 5
View more cards

Comments

No comments have yet been made

Similar Physics resources:

Physics
Physics
Physics
See all Physics resources »See all All of P2 resources »