Waves (Seneca) Flashcards
1
Q
Waves transfer energy from …
A
one place to another without transferring matter.
2
Q
Wave motion (the movement of waves) can be shown by the …
A
vibrations of a spring or by water waves.
3
Q
When a wave travels along the surface of the water, a cork floating on the surface of the water will only …
A
move up and down as the wave passes.
4
Q
Wave speed =
A
frequency × wavelength
5
Q
Frequency of a wave =
A
1 / time period
6
Q
Wave frequency =
A
number of oscillations / time
7
Q
number of oscillations / time
A
= wave frequency
8
Q
The amplitude of a wave is the …
A
largest distance that a point on the wave moves from its rest position.
9
Q
The wavelength is the …
A
distance between two adjacent wavefronts.
10
Q
A transverse wave causes the particles in the medium (the substance that the wave travels through) to …
A
vibrate at right angles to the direction of the wave’s motion.
11
Q
At what angle do the particles move relative to a transverse wave’s direction?
A
90 degrees (right angle)
12
Q
Examples of longitudinal waves are …
A
sound waves
13
Q
In what position do particles end up after a transverse wave has passed?
A
Same position
14
Q
Water waves can be set up in a ———- , where a rod at one end of a tank of water creates a series of ripples.
A
Ripple Tank
15
Q
Water waves can be set up in a Ripple Tank, where a …
A
rod at one end of a tank of water creates a series of ripples.
16
Q
bright light shone through the water onto a sheet of paper shows the ripples on the water very clearly as a series of parallel lines travelling along with constant speed.
These parallel lines are the peaks of the ripples on the water. We call them …
A
wavefronts
17
Q
What is the distance between two wavefronts?
A
Wavelength
18
Q
The wave speed (metres per second, ms-1) of a wave is equal to …
A
its frequency (Hertz, Hz) multiplied by its wavelength (metres, m).
19
Q
A longitudinal wave causes the medium’s particles to …
A
vibrate in the same direction as the wave’s motion.
20
Q
Here are some example of longitudinal waves:
A
- Sound waves
- P-waves
21
Q
A bright light shone through the water onto a sheet of paper shows the ripples on the water very clearly as a series of ———— lines travelling along with constant speed.
A
parallel
22
Q
When waves travel from one medium to another, their speed and wavelength change but their ——— stays the same.
A
frequency
23
Q
When waves travel from one medium to another, their ————- change but their frequency stays the same.
A
speed and wavelength
24
Q
The speed of a wave changes when it travels from …
A
one medium to another.
25
The ——— of a wave also changes when it travels from one medium to another.
wavelength
26
The speed and the wavelength are …
directly proportional.
27
If the speed doubles, the wavelength ...
doubles
28
If the speed halves, the wavelength…
halves.
29
The frequency of the wave does not change because …
the source is producing the same number of oscillations (vibrations) per second.
30
Waves can be ————- at the boundary between one medium (material) and another.
reflected, refracted, absorbed and transmitted (passes through)
31
If the wave crosses to the new medium at an angle (not 90 degrees), the change in the wave’s speed will …
cause the direction of the wave’s motion to change and the wave will appear to bend.
32
If the wave crosses to the new medium at an ————- , the change in the wave’s speed will cause the direction of the wave’s motion to change and the wave will appear to bend.
angle (not 90 degrees)
33
If the wave crosses to the new medium at an angle (not 90 degrees), the change in the wave’s speed will cause the direction of the wave’s motion to change and the wave will appear to bend.
This is called ...
refraction
34
Reflection happens when a …
wave hits a flat surface (plane) and bounces off.
35
What is transmission?
Waves carry on travelling through a new material.
This often leads to refraction.
36
What is absorption?
When waves meet some materials, the energy is absorbed by the material.
37
What type of material absorbs the most light?
Matte black
38
The angle of incidence is the …
angle between the incident (incoming) light ray and the normal.
39
The normal is a …
line at 90 degrees to the plane.
40
Light can be reflected by a …
plane (flat surface).
41
The angle of reflection is the …
angle between the reflected light ray and the normal.
42
The law of reflection states that …
the angle of incidence = the angle of reflection.
43
Light is refracted when it travels from …
one medium to another and changes speed.
44
If light speeds up on entering a new medium, this medium is “—————”.
less optically dense
45
If light speeds up on entering a new medium, this medium is “less optically dense”.
The light is refracted ———— from the normal - the angle of refraction is larger than the angle of incidence.
further
46
If light speeds up on entering a new medium, this medium is “less optically dense”.
The light is refracted further from the normal - the angle of refraction is ——— than the angle of incidence.
larger
47
If light speeds up on entering a new medium, this medium is “—————-”.
The light is refracted further from the normal - the angle of refraction is larger than the angle of incidence.
less optically dense
48
What will happen to the wave if the light enters a less optically dense material?
It will speed up
49
Light speeds up when …
entering a less optically dense medium.
50
Light speeds up when entering a less optically dense medium. When this happens, some light is …
refracted and some light is reflected.
51
What is internal
reflection?
when some light is refracted and some light is reflected
52
What is angle of
refraction?
The angle between the refracted light and the normal.
53
If the angle of incidence is the same as the critical angle, the light will …
travel along the boundary of the 2 mediums.
54
If the angle of incidence is the ——- as the critical angle, the light will travel along the boundary of the 2 mediums.
same
55
If the angle of incidence ——— the critical angle, then all the light will be reflected. This is called total internal reflection.
exceeds
56
If the angle of incidence exceeds the critical angle, then ———— . This is called total internal reflection.
all the light will be reflected
57
If the angle of incidence exceeds the critical angle, then all the light will be reflected. This is called …
total internal reflection.
58
Total internal reflection means that …
all of the light is reflected and no light is refracted.
59
If the angle of incidence is the same as the critical angle, the light will …
travel along the boundary of the two mediums.
60
Sound waves are ————— waves.
longitudinal
61
Sound waves are longitudinal waves. They can travel through solids by …
causing vibrations in the solid.
62
Sound is produced by the ...
vibration of particles in a medium (the substance that waves travel through).
63
The vibrations mean that sound waves travel in a series of …
compressions (where the medium is squashed together) and rarefactions (where the medium is stretched apart).
64
Ultrasound has a frequency …
above 20,000Hz.
65
Our ears can detect vibrations (compressions and rarefactions) and transfer the information to our brain via our …
auditory nerve.
66
Our ears are sensitive to (can hear) a range of frequencies between …
20Hz and 20,000 Hz.
67
Ultrasound has a frequency above 20,000Hz. Humans cannot hear sounds with frequencies this high, but ————- can.
other animals
68
Dog whistles have frequencies above 20,000Hz, which is why …
humans cannot hear them.
69
Ultrasound is also used by …
doctors to perform scans of a developing foetus.
70
The range of frequencies that we can hear changes with age.
Elderly people tend to become …
less sensitive to sounds with a higher frequency.
71
Sound needs to travel through a ...
medium
72
The more rigid the medium is, the ——— the speed of the sound wave through the medium.
higher
73
The ——— rigid the medium is, the higher the speed of the sound wave through the medium.
more
74
The more compressible the medium is, the ——- the speed of the sound wave through the medium.
slower
75
The ——- compressible the medium is, the slower the speed of the sound wave through the medium.
more
76
Gases are ————- , so the speed of sound in a gas is very slow.
readily compressible (easy to squash)
77
Gases are readily compressible (easy to squash), so the speed of sound in a gas is …
very slow.
78
Solids are significantly ———— and gases and are very hard to compress.
more rigid than liquids
79
Solids are significantly more rigid than liquids and gases and are very hard to compress.
Therefore, the speed of sound in solids is much …
higher than in liquids or gases.
80
Liquids are more ————— than gases, so the speed of sound in liquids is much higher than in gases.
rigid and less compressible
81
Liquids are more rigid and less compressible than gases, so the speed of sound in liquids is …
much higher than in gases.
82
——— can be used to measure the speed of sound.
Echoes
83
Describe the experiment for Measuring the Speed of Sound. (Short)
Two people stand a measured distance from a tall vertical wall. This distance should ideally be about 100m.
The first person bangs two wooden blocks together to make a sharp sound and repeats this every time the echo is heard. Starting counting from zero, the second person uses a stopwatch (timer) to measure the time taken for a number of claps – 50 or 100.
In the time between two successive claps, the sound travels to the wall and back.
84
The speed of sound can be calculated from the following relationship:
speed of sound = ( distance to wall × 2 × number of claps (N)) ÷ time taken for N claps.
85
Sound is a wave. Because of this, it can be:
- Absorbed
- Transmitted
- Reflected
- Refracted
86
When ultrasound waves meet a boundary between two different materials, some are reflected. We can work out how far away a boundary is based on …
how long it takes for reflections to reach a detector.
87
We can use ultrasound waves for both …
medical and industrial imaging.
88
Ultrasound uses:
- training dogs (dog whistles)
- industry
- measuring water depth
- medicine
89
Doctors use ultrasound to …
perform scans of a developing foetus.
90
Ultrasound waves can ———- the body.
pass through
91
Whenever they reach a boundary between two different materials, some will be reflected. We can detect the ...
reflected waves
92
Whenever they reach a boundary between two different materials, some will be reflected. We can detect the reflected waves.
A computer processes the …
timing and distribution of these waves. The computer uses these to produce a video image of the foetus.
93
We can use echo sounding to …
detect objects in deep water and also to measure water depth.
94
We can use ———- to detect objects in deep water and also to measure water depth.
echo sounding
95
We send an ultrasound pulse into the water. When this pulse hits any surface, it is …
reflected back.
96
We can work out the distance travelled by the sound wave by …
recording the time between us sending the pulse and detecting the reflection.
97
We can use ultrasound in industry to …
find flaws in objects or materials (e.g. pipes or wood).
98
When ultrasound waves enter a material, they will normally be reflected by the far side of the material.
If there is a flaw (e.g. a crack), the waves will …
be reflected sooner. This tells us that there is a problem.
99
Earthquakes produce two types of seismic waves:
- P-waves (primary)
- S-waves (secondary)
100
Seismic waves are …
waves which travel through the Earth.
101
P-waves are …
longitudinal, seismic waves.
102
P-waves travel at …
different speeds through solids and liquids.
103
S-waves (secondary) are …
transverse, seismic waves.
104
S-waves cannot travel through …
liquids (only through solids).
105
Seismic waves cannot travel through all parts of the earth because …
the earth is made up of different materials.
106
Seismic waves cannot travel through all parts of the earth because the earth is made up of different materials.
Scientists have used this principle to …
work out the different materials that the earth is made up of.
107
By detecting seismic waves from Earthquakes, scientists have worked out that …
the Earth has a solid core surrounded by a liquid outer core.
108
In a sound wave, in which direction do the particles move?
In the same direction as the wave's motion.
109
When light moves into a less optically dense medium, what happens?
- the light speeds up
- the angle of refraction is greater than the angle of incidence
110
If the incident light is at the critical angle, what will the refracted light do?
Travel parallel to the boundary of the two mediums.
111
All electromagnetic waves are --------- waves that travel at the same speed (or velocity) in a vacuum.
transverse
112
All electromagnetic waves are transverse waves that travel at ...
the same speed (or velocity) in a vacuum.
113
All electromagnetic waves are transverse waves that travel at the same speed (or velocity) in a vacuum. To simplify things, we assume that the speed of electromagnetic waves in ...
air is the same as that in a vacuum.
114
There is a continuous spectrum of EM waves and the waves transfer ...
energy from the source to the absorber of the wave.
115
what is the anagram to remember em waves?
roman
men
invented
very
useful
x-ray
guns
116
what ,in order of lowest to highest frequency, is the em spectrum?
radio
microwave
infrared
visible light
ultraviolet
x-ray
gamma
117
As you move from gamma rays to radio waves, the wavelengths increase and the frequencies ...
decrease
118
As you move from gamma rays to radio waves, the wavelengths -------------- and the frequencies decrease.
increase
119
Gamma rays have the shortest wavelength and the ---------frequency.
highest
120
Gamma rays have the --------wavelength and the highest frequency.
shortest
121
Radio waves have the ----------- wavelength and the lowest frequency.
longest
122
Radio waves have the longest wavelength and the --------- frequency.
lowest
123
Gamma rays also carry the ----------- amount of energy than any other wave in the electromagnetic spectrum.
most
124
Wave energy ----------- with frequency.
increases
125
Wave energy ---------- with wavelength.
decrease
126
Gamma rays are used for ...
medical imaging and therapy, astronomy, sterilisation and food preservation.
127
Gamma rays are extremely ---------------------- to living tissues and cells.
penetrating and damaging
128
Gamma rays carry the most energy. We can use gamma rays to destroy ...
bacteria and tumours.
129
X-rays penetrate ...
soft materials (like body tissue).
130
Bones are ------ materials that absorb X-rays.
dense
131
Bones are dense materials that -------- X-rays.
absorb
132
Bones are dense materials that absorb X-rays. We can use X-rays to ...
build a shaded image of bones and body tissue.
133
Low-energy X-rays are used for ...
medical and industrial imaging.
134
High-energy X-rays are used to ...
treat cancer.
135
X-rays are also used for ...
security purposes to detect weapons in airports (and other places).
136
A risk of X-rays are that they are ...
highly ionising (can damage body cells), even in low doses.
137
Due to the dangerous nature of X-rays, exposure to X-rays should always be kept to a ...
minimum
138
People working with X-ray equipment should always ...
shield themselves to prevent exposure to X-rays.
139
People working with X-ray equipment should always shield themselves to prevent exposure to X-rays.
These people will ...
place materials (metals like lead) between themselves and the X-rays.
140
Ultraviolet light is used in ...
medical and forensic photography, air purification, disinfection and medical therapy.
141
Ultraviolet light can also be used to ...
detect fake bank notes.
142
Exposure to too much ultraviolet light can cause ...
skin burns, skin cancer and cataract formations in the eye.
143
In lamps, UV photons -------- atoms. The atoms then release visible light.
excite (gives energy to)
144
In lamps, UV photons excite (gives energy to) atoms. The atoms then ...
release visible light.
145
In lamps, UV photons excite (gives energy to) atoms. The atoms then release visible light.
In sun tanning, UV excites ...
(gives energy to) skin cells. The skin cells then change colour.
146
In lamps, UV ------ excite (gives energy to) atoms. The atoms then release visible light.
photons
147
One of the risks of Infra-red radiation is that it can cause ...
serious skin burns if emitted from high-intensity sources.
148
Infra-red radiation is used in ...
TV controls.
149
Infra-red can also be used for ...
security purposes, such as in intruder alarms by detecting body heat.
150
Infra-red cameras can detect a ...
range of frequencies. These frequencies can be shown in different colours to depict images.
151
We should always ------ any exposure to microwaves.
reduce
152
As with X-rays, microwaves always have ------------------ between the source of microwaves and living tissue.
some sort of shielding
153
Microwaves have a ----------------- to penetrate the Earth’s atmosphere and to reach satellites.
high enough frequency
154
Microwaves have a high enough frequency to ...
penetrate the Earth’s atmosphere and to reach satellites.
155
Microwaves travel in straight lines through the atmosphere. This makes them good for ...
transmitting (sending) signals.
156
Microwaves travel in ----------------- through the atmosphere. This makes them good for transmitting (sending) signals.
straight lines
157
Microwaves are absorbed by water, heating up the water in the process. This makes microwaves useful for ...
cooking food because food contains lots of water.
158
Microwaves are absorbed by water, ----------- in the process. This makes microwaves useful for cooking food because food contains lots of water.
heating up the water
159
Microwaves are -------- by water, heating up the water in the process. This makes microwaves useful for cooking food because food contains lots of water.
absorbed
160
Microwaves are also used to transmit signal from a ...
nearby phone mast (transmitter) to a mobile phone.
161
Microwaves are used for the purpose of ------------ communications (transmitting signals between stations on Earth and satellites).
satellite
162
Because humans are -------------, exposure to microwaves could have a harmful effect.
largely made up of water
163
Radio waves are used for ...
radio and TV communications.
164
Because radio waves have --------------- , they can be transmitted (sent) around the Earth’s surface and around buildings without interference.
long wavelengths
165
Because radio waves have long wavelengths, they can be ...
transmitted (sent) around the Earth’s surface and around buildings without interference.
166
At high intensities, radio waves can cause ...
internal heating of living tissue with potentially harmful effects.
167
Electromagnetic waves can be produced by ...
electrical circuits and by changes in atoms.
168
Oscillations (repeating variations) in electrical circuits can produce ...
radio waves.
169
--------- in electrical circuits can produce radio waves.
Oscillations (repeating variations)
170
When radio waves are absorbed, they can create an ...
alternating current with the same frequency as the radio wave itself.
171
When radio waves are absorbed, they can create an alternating current with the same frequency as the radio wave itself.
This means that ...
radio waves can lead to oscillations in an electrical circuit.
172
Changes in atoms and the nuclei of atoms can result in electromagnetic waves being ...
generated or absorbed over a wide frequency range.
173
Changes in atoms and the nuclei of atoms can result in ------------ waves being generated or absorbed over a wide frequency range.
electromagnetic
174
Gamma rays originate from ...
changes in the nucleus of an atom.
175
Electromagnetic radiation can be produced by:
- changes in atoms
- electrical circuits
176
We use visible light in ---------- because it can be totally internally reflected.
optical fibres
177
We use visible light in optical fibres because ...
it can be totally internally reflected.
178
We use visible light in optical fibres because it can be totally internally reflected.
This means that we can ...
transmit signals (information) along optical fibres without the signals (information) getting lost.
179
We use visible light to ...
see the world around us and in fibre optics.
180
Traditionally, we say that there are seven colours of light in the spectrum :
Red, Orange, Yellow, Green, Blue, Indigo and Violet.
181
Transparent objects also transmit light without ...
scattering the rays.
182
Opaque objects either ---------- all light that hits them.
reflect or absorb
183
Translucent objects transmit light but the rays are ...
scattered.
184
Light can be reflected from a surface in two ways :
- Diffuse reflection
- Specular reflection
185
Diffuse reflection happens when ...
light is reflected by a rough surface.
186
Specular reflection happens when ...
light is reflected by a smooth surface in a single direction.
187
Each colour within the visible light spectrum has its own ...
narrow band of wavelength and frequency.
188
If all wavelengths are reflected equally, the opaque object looks ...
white.
189
If all wavelengths are absorbed, the object looks ...
black.
190
When an opaque object looks like it has a particular colour, it is ...
reflecting light of that particular wavelength (colour) and absorbing all other wavelengths.
191
Colour filters absorb ...
certain wavelengths (colours) and transmit other wavelengths (colours).
192
Objects appear as different colours based on ...
how the colours of white light are absorbed and reflected.
193
If a blue book was looked at through a red filter, the book would look black.
This is ...
because the red filter will only allow red light to pass through.
It will absorb all other colours of light.
194
A blue book looks blue because ...
every colour from the visible light spectrum is absorbed except for the colour blue, which is reflected.
195
An ----- sends pulses of high frequency sound waves.
emitter
196
A lens forms an image by ...
refracting light.
197
There are two main types of lens:
concave and convex.
198
A convex lens is ...
curved on both sides and is wider at the middle than at the edges.
199
The principal focus of a convex lens is the ...
place where all the rays hitting the lens parallel to the axis meet.
200
The distance from the lens to the principal focus is called the ...
focal length.
201
A convex lens is also called a ...
converging lens.
202
A concave lens is ...
wider at the edges than in the middle.
203
When parallel rays of light enter a concave lens, they ...
disperse (spread out).
204
In concave lens, if you trace back along the paths of the dispersed rays, they will look like ...
they came from the principal focus that is behind the lens.
205
A concave lens is also called a ...
diverging lens.
206
Which lens is wider in the middle and thinner at the ends?
Convex
207
Which lens is thinner in the middle and wider at the ends?
concave
208
Convex lenses produce images that are either ...
real or virtual.
209
Concave lenses only produce
------ images.
virtual
210
A virtual image appears on the ...
same side of the object
211
We cannot project virtual images onto a ...
screen.
212
Convex lenses produce images that are ...
either real or virtual.
213
A real image appears on the --------- to the object.
other side of the lens
214
A virtual image appears on the same side of the object. We cannot project virtual images onto a ...
screen.
215
We can use this equation to calculate the magnification a lens produces:
magnification = image height ÷ object height
216
Magnification is a ratio. It has no ...
units.
217
What type of image can we project on to a screen?
real
218
When drawing ray diagrams:
- Draw the principal axis (the horizontal line that goes straight through the middle of the lens).
- Use the correct lens symbols.
- Mark the principal focus on either side of the lens.
- Draw a dot on the principal axis and label it F.
- Mark the position of the object as an arrow standing on the principal axis.
- Now draw the light rays.
219
what anogram is used to remember the steps for drawing ray diagrams?
Don't
Use
Mark
Draw
Maps
Never
220
How do you Draw a Convex Lens Ray Diagram?
Draw a line from the top of the object to the lens.
From this point on the lens, draw a second line through the principal focus on the other side of the lens.
Draw a third line from the top of the object straight through the middle of the lens.
If the lines meet on the opposite side of the lens, this forms a real image.
Draw the image as a vertical arrow connecting the point where the lines cross to the principal axis.
If the lines do not meet (diverging rays), this forms a virtual image.
221
What is the anogram you use for Drawing a Convex Lens Ray Diagram?
Draw
from
Destiny
if
dogs
infer
222
How do you Draw a Concave Lens Ray Diagram?
Draw a straight line from the top of the object to the lens.
Draw a dotted line from the principal focus (on the same side of the lens) to the point where the first line meets the lens.
Continue the second (dotted line) through the lens as a solid line.
Draw a third line from the top of the object through the middle of the lens.
The top of the image (virtual and the right way up) is where the dotted line meets the third line.
Draw a vertical arrow on this image from the principal axis to where the lines meet.
223
what is the anogram for How to Draw a Concave Lens Ray Diagram?
Don't
Dry
Cats
Do
the
Dance
224
What is the name of the horizontal line that goes straight through the middle of the lens?
principal axis
225
In convex ray diagram, light rays ...
focus to a point.
226
In concave ray diagram, Light rays ...
spread out.
227
Infrared radiation can transfer thermal energy without a ...
medium (substance to travel through).
228
All bodies (objects) emit ...
radiation.
229
The ------------ emitted by the Sun transmits thermal (heat) energy to the Earth.
infra-red radiation
230
Infra-red radiation does not need a medium, so can still travel through ...
space.
231
Surfaces can either -------------------------- infra-red radiation.
reflect, absorb (take in), or emit (give out)
232
Black surfaces are good emitters, ------ absorbers and poor reflectors.
good
233
Black surfaces are good emitters, good absorbers and --------- reflectors.
poor
234
Black surfaces are -------- emitters, good absorbers and poor reflectors.
good
235
White surfaces are --------- reflectors of infra-red radiation.
good
236
White surfaces are ---- emitters and absorbers of infra-red radiation.
poor
237
Shiny surfaces of a colour are ---------- absorbers of radiation than dull surfaces of the same colour.
poorer
238
Shiny surfaces are --------------- emitters and better reflectors than dull surfaces of the same colour.
poorer
239
A perfect black body is an object that ...
absorbs all of the radiation incident on it.
240
A black body does not ...
reflect or transmit any radiation.
241
Since a good absorber is also a good emitter, a perfect black body would be the ----------- possible emitter.
best best
242
The amount of radiation emitted by a body (object) depends on its ...
surface area and surface temperature.
243
Bodies with a large surface area will emit radiation ...
faster.
244
Bodies with a ---------- surface temperature will emit radiation faster.
higher
245
All bodies (objects) emit ...
radiation.
246
A body at constant temperature absorbs radiation at the same rate that it ...
emits radiation.
247
An object will always transmit (send) heat from a ...
hotter area to a colder area.
248
An object will always transmit (send) heat from a hotter area to a colder area.
Radiators work based on this principle.
This means that when an object’s internal temperature is higher than the temperature of the environment around it, the rate of emission will be ...
higher than if the object were in a warmer environment.
249
Black bodies are perfect absorbers and emitters of radiation - they never ...
reflect or transmit radiation.
250
The rates of absorption and emission can be affected by:
- Surface area
- External temperature
- Internal temperature
251
The temperature of a body (object) depends on the rate of ...
absorption of radiation and the rate of emission of radiation.
252
Objects get ------ if they absorb more radiation than they emit.
hotter
253
What happens to a body which absorbs the same amount of radiation as it emits?
its temperature stays the same
254
The process behind the greenhouse effect is:
1. The sun emits short wavelength infrared radiation that enters the atmosphere and travels towards the Earth’s surface.
2. The Earth absorbs some of this radiation, but long wavelength radiation is reflected back into the atmosphere.
3. Greenhouse gases (e.g. carbon dioxide, methane, water vapour) can't absorb the frequency of radiation emitted by the Sun. But they can absorb the longer wavelength reflected radiation.
4. The gases then re-radiate this energy in all directions, including back towards Earth.
5. This increases the temperature at the Earth’s surface.
255
Greenhouse gases are unable to absorb the frequencies of radiation that arrive from the Sun. However, they do absorb some -------- radiation before re-radiating it in all directions, including back towards Earth.
reflected
256
There is a ------- between heat energy absorbed by the Earth and emitted by the Earth.
balance
257
Absorbed sunlight is balanced by ...
heat radiated from Earth’s surface and atmosphere.
258
Most heat escapes from areas ...
just north and south of the equator, where the surface is warm, but there are few clouds.
259
Along the equator, ------- prevent heat from escaping.
persistent clouds
260
------ Watts per square metre of solar energy falls on the Earth.
340
261
------ of solar heat is reflected back into space - primarily by clouds, but also by other bright surfaces and the atmosphere itself.
29%
262
29% is reflected back into space - primarily by ...
clouds, but also by other bright surfaces and the atmosphere itself.
263
About ----- of incoming energy is absorbed in the atmosphere by atmospheric gases, dust, and other particles.
23%
264
About 23% of incoming energy is absorbed in the atmosphere by ...
atmospheric gases, dust, and other particles.
265
About 23% of incoming energy is absorbed in the atmosphere by atmospheric gases, dust, and other particles.
The remaining 48% is absorbed at the ...
surface.
266
About 23% of incoming energy is absorbed in the atmosphere by atmospheric gases, dust, and other particles.
The remaining ---- is absorbed at the surface.
48%
267
Why is it important to maintain satisfactory levels of greenhouse gases on earth?
Without greenhouse gases, temperatures would be too low to support life.
However, high concentrations of greenhouse gases cause the temperature to rise too high, which also threatens life on Earth.
268
What happens to energy from the Sun which hits the Earth:
- Absorbed by the Earth's surface
- reflected by atmosphere
- absorbed by atmosphere
269
Which type of lens focuses light onto a principal focus?
convex
270
Heat radiation is transmitted via which form of wave?
infrared
271
What distinguishes one colour from another?
wavelength
