Physics Flashcards
0
Q
On which planet would you weigh the least?
A
The planet which is the farthest away from the sun.
1
Q
What makes objects have a greater attractive force?
A
The greater the mass of the object.
The closer the objects are.
2
Q
What is a moon?
A
The moon is a large natural satellite which orbits a planet.
3
Q
What is a lunar month?
A
A lunar month is when a moon orbits a planet. Our moon orbits Earth once every 28 days.
4
Q
How far is our moon?
A
Approx. 380,000km away.
5
Q
What are the phases of the moon?
A
They are the changes in the shape of the moon. This happens because we only see the part of the moon which is reflects light from the sun.
6
Q
What other two types of an eclipse and how are they different?
A
Solar eclipse: When the moon passes between the sun and the earth and blocks the light from touching Earth.
Lunar eclipse: When the earth is in the way so that sunlight doesn’t get to the moon.
7
Q
What is a comet?
A
A large piece of rock and ice which orbits the sun. They travel fast when they are close to the sun because of the gravitational force.
8
Q
How long does it take for the Earth to spin on it’s axis?
A
24 hours.
9
Q
How long does it take for the Earth to orbit the sun?
A
365.25 days
10
Q
Where is the asteroid belt?
A
Between Mars and Jupiter
11
Q
Order of planets…
A
Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune Pluto
Many very energetic men jogged slowly upto Newport Pagnell
12
Q
2 ways to increase the strength of an electromagnet
A
Increase the current
Increase the number of turns on the coil around the iron
13
Q
Two uses of an electromagnet
A
Electric bell or Scrapyard electromagnet (used to pick up cars)
14
Q
What do magnets attract?
A
Materials like iron, steel, nickel, cobalt and metals.
15
Q
What is an electric current?
A
An electric current is a flow of electric charge. Electric charge flows when there is voltage present across a conductor.
16
Q
How do we measure the size of an electric current?
A
With ammeters in amperes or amps. (A)
17
Q
Does the current get used up in a circuit?
A
No
18
Q
Power is measured in…
A
Watts
19
Q
What is a series and parallel circuit and how are they different.
A
Series: They have no branches or junctions and have only one path to follow. They can be turned off by only one switch.
Parallel: These have branches and junctions. There is more than one path for the circuits to flow in. Switches can be put into the circuit to turn on or off just one part of the circuit. The size of the current maybe different
20
Q
What’s a battery?
A
Several cells connected together produce a large current. Several cells connected together like this is called a battery.
21
Q
What are the three ways heat can travel?
A
Conduction, convention and radiation
22
Q
What’s an insulator?
A
Keeps in heat or stops currents flowing.
23
Q
Examples of alternative energy. Give at least 3
A
Geothermal Tidal power Solar energy Hydroelectricity Wave power Wind energy Biomass
24
Fossil fuels...
Coal
Oil
Gas
25
Energy: Name at least 5/10.
```
Heat or thermal energy
Electrical energy
Gravitational potential energy
Nuclear energy
Stored energy
Chemical energy
Light energy
Sound energy
Kinetic energy
Elastic potential energy
```
26
What happens after energy is used?
Energy can't be destroyed and it can't disappear
| It is transferred into different forms of energy e.g. light can become electrical energy.
27
How do we hear?
Soundwaves are gathered by the outer ear. Soundwaves make the eardrum vibrate.
The vibration is amplified by 3 small bones.
This vibrates through a liquid in your ear and causes hairs to vibrate.
The hair passes signals through the auditory nerve to the brain.
28
How do we measure loudness?
Decibels (dB)
29
Where does sound come from?
Vibrations
30
What does the amount of waves per second mean?
The more waves that vibrate quickly the higher the pitch.
| Less waves means a lower sound/lower frequency.
31
How do sound waves travel?
Through a solid, liquid or gas in compressions and rarefactions.
Sound can't travel through vacuum
32
Which is faster. Sound or light?
Sound travels at 340 m/s.
| Light travels at 300,000,000 m/s
33
What is refraction?
It is when a ray of light hits a glass block. It then bends towards the normal,90°. when it leaves the glass block, it leaves at an angle parallel to the original ray.
(If light hits the glassblock at 90° it leaves the glass block at 90°)
34
What is this dispersion?
(White light is a mixture of all coloured lights)
It is when white light travels through a prism and the different colours are separated by different amounts in the order of the rainbow. This band of colours is called a spectrum
35
What does a filter do?
It lets through a certain colour e.g. A green light will become separated from the spectrum and pass through a green filter but not a blue one.
36
What are the different lenses?
A converging lens refracts the lights so that rays of light are brought together.
A diverging lens refracts light so that the rays of light are spread out.
37
How is light reflected from a plane?
It is reflected so that the angle of incidence is equal to the angle of reflection, measured from the normal.
38
What's opaque, translucent and transparent?
Not see through at all, letting through no light.
Lets through a bit of light but can't see clearly.
Lets through all light and is see through.
39
What is pressure?
Pressure is a measure of how concentrated or spread out a force is.
40
What is the equation to calculate the pressure created by a force?
Pressure = force / area
Or
P = F/A
(Pressure is measured in pascals (Pa))
41
What's a moment?
The turning effect of a force is called a moment.
42
What is the equation to calculate the size of the moment?
Moment of a force =
| force X perpendicular distance of force from pivot.
43
Which direction does friction act?
Against motion
44
Suggest two ways to reduce friction
Streamline - it is made to cut through the air.
Lubricants - things like wax reduce friction
45
What is terminal velocity?
It is a constant speed by balanced forces
| E.g. As a skydiver falls, gravity pulls him down meanwhile air resistance slows him from from falling
46
Force is measured in...
Newtons
47
How do you calculate the speed, distance or time?
Speed = Distance/Time
To work out the rest, you put it in a triangle.
D
S T
E.g.
D = s x t
S = d / t
T = d / s
48
Difference between speed and velocity...
Speed is how fast an object is moving.
Velocity is how fast an object is moving and in which direction.
49
What's the formula for specific heat capacity?
Energy (j) = mass (kg) x shc (j/kg) x temperature change
50
Ways to insulate a house. Say 3
```
Vacuums
Double glazed windows
Foam or air wall cavities
Loft and roof insulation
Carpets and underlays
Draft proofing
Curtains
```
51
Water in desert ...
```
Dig hole
Put cup in hole
Cover hole with cling film material
Put rock above cup on cling film
Wait till it gets cooler
```
52
What's conduction?
Heat transfer in a solid due to the vibration of particles near to each other.
53
What's convection?
Heat transfer in a gas or liquid when the particles heat and gain energy, lose density, rise, lose energy, gain density and fall.
54
What's radiation?
Heat transfer by heat travelling in straight waved lines in a space or spaces between particles. They can travel through a vacuum. Ultraviolet and infrared.
55
Why are metals such good conductors?
They are good conductors and heat up quickly as they have free electrons which carry heat energy and vibrations while moving.
56
Are liquids and gasses good insulators?
Yes as they don't allow heat transfer through conduction.
57
What's a conductor?
A material that transmits or conducts heat well.
58
What's an insulator?
A material which doesn't allow energy or heat to transmit easily.
59
PQ
| Why do birds ruffle their feathers and look fatter in winter?
Their feathers trap air and, due to the air particles, air is a poor conductor / good insulator.
60
Without bike handle grips, why do your hands get cold faster?
Because the metal has free electrons, it takes heat energy away from your hands quicker due to conduction.
61
Strength of bonds between states:
Solid - strong
Liquid - weak
Gas - barely any
62
How does aluminium foil reduces heat loss?
It reflects the heat back into the room.
63
How does heat travel to earth?
By radiation; by infrared waves, similar to light waves.
Can be
Reflected
Absorbed
Travel through vacuum
Same speed as light
64
What surfaces are the best emitters and absorbers?
Matt black
65
What surfaces are the worst emitters and absorbers?
Silver / shiny
66
What's evaporation?
When the surface layer of particles in a liquid gain energy and move around, changing state from liquid into gas.
67
What's condensation?
When particles lose energy and move about less, changing state back from a gas to a liquid
68
Factors which heat evaporation (5) :
```
Heat
Wind speed or the movement of particles away from the heat source
Low boiling points e.g. alcohol
Surface area
Pressure
```
69
How do draughts transfer heat?
By convection
70
9 main forms of energy: ( kids hate learning G C S E energy names)
```
Kinetic (movement)
Heat (thermal)
Light
Gravitational potential
Chemical
Sound
Electrical
Elastic potential
Nuclear
```
71
What is energy measured in?
Joules
| J
72
Can energy be created or destroyed?
No, it just changes form
73
What happens when energy spreads out?
It becomes less useful
74
Is the total amount of energy constant?
Yes
75
How is energy transfer shown/represented?
```
Through flow (sankey) diagrams.
(Different sized arrows)
```
76
What's force measured in?
Newtons
| N
77
What's power measured in?
Watts
W
(Equivalent to 1 joule per second)
78
How to work out energy by power and time
Energy = power x time
79
How to work out energy by force and distance
Energy = force x distance
80
What's the equation for the efficiency of a device?
% efficiency = useful energy out / total energy in x 100
81
If 20j electrical energy is the energy input into a light bulb,10j light energy and 10j heat energy is the output, what is the wasted energy and what's the efficiency?
The wasted energy is the heat energy and the efficiency is 50%
( % = 10 / 20 = 0.5 0.5 x 100 = 50 )
82
How do you work out 1 kWh (1 unit)
Example
Energy transfer = power in kW x time in hrs
= 2 kW x 3 hrs
= 6 kWh (= 6 units)
83
How do you work out the cost of electricity?
Cost of electricity = number of units (kWh) x cost of unit
Example
Energy transfer = power in kW x time in hrs
= 2 kW x 3 hrs
= 6 kWh (= 6 units)
Cost = 6 kWh x 8p
= 48p
84
How many W is a kW?
1000w
85
What's a sankey diagram?
A rough diagram showing the amount of energy input and output.
86
How do we generate electricity from power stations?
In a boiler, fossil fuels or nuclear gas are burned to heat the water in pipes.
The water then turns to steam and goes through pipes which turns turbines.
The movement of the turbines powers a generator (meanwhile the condenser cools the steam back to water and into the boiler).
The generator creates electricity which goes to the transformer and is 'stepped up'.
It travels along the national grid until it reaches our homes and is stepped down
87
What are the main alternative energy sources?
| 7
```
Wind
Biomass
Geothermal
Tidal
Wave
Solar
Hydroelectric
```
88
Pros and cons of: Wind energy
| 3
Pros:
Land can still be used
No pollution
No environmental impact
Cons:
Expensive - Not cost affective
Scars environment
Requires wind and may break in storms.
89
Pros and cons of: Biomass
3
(Biofuel - fuel made of living things / Biomass - fuel made by rotting and burning plants and wood)
Pros:
There is always waste to use and burn e.g. Rubbish or chicken poop.
Reduces dependency on fossil fuels
Less greenhouse gas emissions
Cons:
Limited sources
Not completely reliable
Causes air pollution
90
Pros and cons of: Geothermal
| 3
Pros:
Sustainable
Doesn't require much space
Energy is available daily and is a free source
Cons:
Only possible where hot rocks are near the surface
Drilling can release harmful, poisonous gasses
Energy can't be transported; can only be used in that area
91
Pros and cons of: Tidal
| 3
Pros:
Sustainable - relies on the moon
No waste or emissions
80% efficient and is a free source
Cons:
Limited areas
Kills some animals and habitats
Ugly and expensive
92
Pros and cons of: Wave
| 3
Pros:
Sustainable
Pollution free
Free energy source
Cons:
Difficult and complex to harness power and build stations
Salt water easily damages some of the components e.g. Corrosion of the metal.
Can break in storms yet are very expensive
93
Pros and cons of: Solar
| 3
Pros:
No cost after built
Not space consuming
Doesn't affect the environment
Cons:
Needs a sunny climate
Expensive to install
Doesn't work at night or when dark
94
Pros and cons of: Hydroelectricity
| 3
Pros:
Can generate energy very quickly
Low maintenance
Reliable
Cons:
Can flood
Can only be built in certain areas
Land can be wasted.
95
What's nuclear fission?
Nuclear power reactors use a reaction called nuclear fission. Two isotopes in common are used such as nuclear fuels are uranium-235 and plutonium-239.
Fission is another word for splitting. The process of splitting a nucleus is called nuclear fission.
Uranium or plutonium isotopes are normally used as the fuel in nuclear reactors, because their atoms have relatively large nuclei that are easy to split, especially when hit by neutrons.
When a uranium-235 or plutonium-239 nucleus is hit by a neutron, the following happens:
the nucleus splits into two smaller nuclei, which are radioactive
two or three more neutrons are released
some energy is released
The additional neutrons released may also hit other uranium or plutonium nuclei and cause them to split. Even more neutrons are then released, which in turn can split more nuclei. This is called a chain reaction. The chain reaction in nuclear reactors is controlled to stop it going too fast.
96
What's nuclear fusion?
Nuclear fusion is a nuclear reaction in which two or more atomic nuclei collide at a very high speed and join to form a new type of atomic nucleus, also releasing energy.
97
Pros and cons of nuclear power:
| 6:5
```
Pros:
We need it
No CO2 or SO2
Less environmental damage
Small amount if nuclear waste is made which can be safely stored
Designed to be safe
Cheaper to run after construction
```
Cons:
Uranium is limited
Nuclear waste produced is radioactive for thousands of years
Leaving waste is irresponsible
No level or radioactivity is safe
To risky especially to human error e.g. Chernobyl
98
What is carbon neutral?
When CO2 from a source is used as much as it is produced.
99
What is carbon capture and storage?
It is the process of capturing waste CO2 from high emission areas e.g. fossil fuel power stations, transporting them to special storage sites then depositing it where it cannot enter the atmosphere, often underground. It can capture up to 90% of waste CO2
100
What is a transformer?
It controls the voltage if an alternating current.
101
What is the formula for power using current, power and voltage?
```
P = V x I
Power = voltage x current
```
102
What's the national grid system?
Nuclear or fossil fuel is burned in the power station
Water is heated to make steam
The steam makes a turbine turn
The turbine turns a generator
The generator produces electricity
The voltage is stepped up to 132kV by the transformer
The energy is transferred through the national grid
The electricity is stepped down to 230V and enters homes
103
Is nuclear energy renewable?
No
104
In a water barrage, what does water gain as it moves to the upper basin?
Gravitational potential energy
105
What's the peak of a wave?
The top, the highest point.
106
What is the trough of a wave?
The bottom of a wave, the lowest point.
107
What is a wavelength?
The full length of a wave, from one peak to the next or one trough to the next.
108
What is the amplitude of a wave?
The furthest extent of a wave, from the middle line.
109
What is the wave frequency?
The number of complete waves per second, measured in Hz
110
What are the 2 main types of wave?
| Plus example
Transverse - up and down wave e.g. Light
Longitudinal - push wave with compressions and rarefactions e.g. Sound
111
What's the wave (speed) equation?
Wave speed = frequency * wavelength
m/s = Hz * m
112
What's the frequency (wave) equation?
Frequency = 1 / time for one cycle
113
What's refraction?
The bending of a wave towards the normal when it passes a denser object, slowing down.
Refraction is the change in direction of a wave due to a change in its transmission medium.
Due to change of medium, the phase velocity of the wave is changed but its frequency remains constant. This is most commonly observed when a wave passes from one medium to another at any angle other than 90° or 0°. Refraction of light is the most commonly observed phenomenon, but any type of wave can refract when it interacts with a medium, for example when sound waves pass from one medium into another or when water waves move into water of a different depth.
Refraction is described by Snell's law, which states that for a given pair of media and a wave with a single frequency, the ratio of the sines of the angle of incidence θ1 and angle of refraction θ2 is equivalent to the ratio of phase velocities (v1 / v2) in the two media, or equivalently, to the opposite ratio of the indices of refraction (n2 / n1):
114
Refraction facts:
| 5
Angle of incidence = Angle of angle of emergent
Different colours have different wavelengths so refract at different amounts (red least).
If speed is reduced, it bends towards the normal; if speed is increased, it bends away from normal.
Property of all waves.
It doesn't bend in if the wave enters at 90°
115
What's reflection?
Reflection is a change in direction of a wave upon striking the interface between two materials. Reflection can occur for sound waves (allowing a person's voice to carry around a corner), water waves, and light waves.
116
Law of reflection
Angle of incidence = Angle of reflection
117
What are electromagnetic waves?
electromagnetic radiation: radiation consisting of waves of energy associated with electric and magnetic fields resulting from the acceleration of an electric charge.
118
What are the electromagnetic waves in order (of longest / lowest wavelength / frequency) :
```
Radio
Microwave
Infrared
(Visible) light
Ultraviolet
X-ray
Gamma
```
119
What are the uses of the electromagnetic waves?
```
Radio - communication and tv / mobile signals
Microwave - cooking
Infrared - security alarms
(Visible) light - seeing and photography
Ultraviolet - tanning beds
X-ray - medical images
Gamma - killing cancer cells
```
120
Properties of electromagnetic waves:
| 4
They all travel at the speed of light
They can all travel through a vacuum
They can be reflected, refracted and defracted
They're all transverse waves
121
What's diffraction?
When waves spread out (curve) when passing an obstacle or gap. The amount of diffraction depends on the wavelength.
The longer the wavelength, the greater the diffraction.
122
How does the size of the gap make a difference during diffraction?
When waves pass a gap or obstacle, if the gap is larger than the wavelength then the waves passing the obstacle will be curved at the edges.
If the gap is the same / similar size as the wavelength then the waves passing the gap will be more (evenly) curved.
123
How are radio and tv waves diffracted?
They can both be diffracted but in different ways.
As radio waves have a longer wavelength, when passing over obstacles, they bend / diffract more.
Because TV waves have a shorter wavelength, they bend / diffract less, meaning people in hilly areas have better radio than tv signal.
Radio refracts more.
124
How do sound waves travel.
In longitudinal (push) waves with compressions and rarefactions.
125
How does amplitude and frequency affect sound?
Frequency: The number of waves in a second. It affects the pitch. The higher the frequency, the higher the pitch.
Amplitude: the size / height of the wave. It affects the volume. The larger the amplitude, the louder the sound.
126
What's the hearing range of an average, healthy human?
20 - 20,000 Hz
Anything above our hearing means ultrasound.
Anything below our hearing means infrasound.
127
What's the Doppler effect?
An increase (or decrease) in the frequency of sound, light, or other waves as the source and observer move towards (or away from) each other. The effect causes the sudden change in pitch noticeable in a passing siren, as well as the red shift seen by astronomers.
128
What's red shift?
The displacement of spectral lines towards longer wavelengths (the red end of the spectrum) in radiation from distant galaxies and celestial objects. This is interpreted as a Doppler shift which is proportional to the velocity of recession and thus to distance.
In physics, redshift happens when light or other electromagnetic radiation from an object is increased in wavelength, or shifted to the red end of the spectrum.
Some redshifts are an example of the Doppler effect, familiar in the change in the apparent pitches of sirens and frequency of the sound waves emitted by speeding vehicles. A redshift occurs whenever a light source moves away from an observer.
129
What's the Big Bang?
The rapid expansion of matter from a state of extremely high density and temperature on a central point which, according to current cosmological theories, marked the origin of the universe.
130
How do distant galaxies display red shift?
The further the galaxy, the more red shifted it is, suggesting that it is moving away from us as it has a larger wavelength. If it were moving toward us (blue shifted) the waves would be more compressed and therefore have a smaller wavelength.
131
Experiment.
| Sound is reflected from a mirror. The mirror is then replaced by glass. Why does the amount reflected decrease?
Because the glass absorbs some of the sound and allows it to pass through whereas the shiny, smooth mirror reflects more and doesn't allow as much to pass.
132
A loudspeaker produces a sound wave at a frequency of 850 Hz.
The wavelength of the sound is 0.4m.
What is the speed of the sound wave?
ws = f * wl
ws = 850 * 0.4
850 * 0.4 = 340
ws = 340
133
What word is used to describe a reflected sound?
An echo.
134
Which electromagnetic wave has the most energy?
Gamma
| A higher frequency means more energy.
135
At what speed do micro waves travel compared to infrared?
The same
136
In what direction does a transverse wave travel?
90° from the source
137
Why would light not refract when entering a medium?
Because it would have entered at 90° and is already towards the normal line.
138
What problem comes from using a sun bed?
Skin cancer
139
What type of electromagnetic wave is used when a traffic light communicates with a driver?
Visible light
140
When a loudspeaker is swung around in circles, what sound will people hear?
A note of varying frequency
141
What does observation and analysis of red shift suggest?
That the universe began from a small, initial point and has been expanding ever since.
