P14.1 1 Reflection of light AQA GCSE Physics P14 light Kerboodle Answers: Page No. 203
1 a i The law of reflection states that the angle of incidence = the angle of reflection. So if the angle of reflection is 20 then the angle of incidence = 200. ii The angle between the incident ray and the reflected ray is 400, because the angle between incident ray and reflected ray = 200+200 = 400. b If the mirror is turned and the angle of incidence is increased to 21 then the angle between incident ray and reflected ray will become 420. a The path of the two rays shown from O after they have been reflected from the mirror is shown in the figure below–
b
ii Since R= infinity for a plane mirror,
By using mirror formula
hence, 1/v+1/u = 2/R
So 1/v=-1/u
v = -u.
Hence proved that the image and objectbare at the same distance from the mirror.
Two plane mirrors are placed perpendicular to each other.
b The angle between the final reflected ray and the incident ray is 1800.
ii Normal N1 perpendicular to normal N2
=1800.
Rays after reflection from two mutually perpendicular mirrors becomes anti parallel.
Hence it can be concluded that the angle A is always equal to 180 whatever may be the angle of incidence.
a The specular and diffuse reflection can be distinguished as-
Reflection from a smooth surface is called specular reflection because parallel light rays are reflected in a single direction.Parallel light rays reflected from a rough surface are scattered in different directions. If you polish a rough surface like a dusty table top to make it smooth, you might see a reflection in the surface. Reflection from a rough surface is called diffuse reflection because the tight is scattered in different directions.
b The image formed by a plane mirror is virtual, upright (the same way up as the object), and laterally inverted (back to front but not upside down). A virtual image is formed at a place where light rays appear to come from after they have been reflected (or refracted). It can’t be projected onto a screen like the movie images you see at a cinema. An image that can be seen on a screen is described as a real Image because it is formed by focusing light rays onto the screen. The aforesaid are the differences between the real and virtual image.
P14.2 Refraction of light AQA GCSE Physics P14 Light Kerboodle Answers: Page No. 205
A light ray from the bottom of a swimming pool refracts at the water surface. Its angle of incidence is 40 degrees and its angle of refraction is 75 degrees.
a
b The swimming pool apoears to be shallower than it is really when viewed from above because the rays of light reaching you from the object at the bottom of the water do not come straight to you, as they would if there was no water between you and the object. The light travels straight as long as it is in the water, but if it emerges obliquely from the water into the air it is bent downward toward the surface. This bending is known as refraction, and it occurs whenever light passes from one transparent medium into another of different density – as, for example, from water to air, or from air to glass. The eyes do not take refraction into account, but judge the position of the object as if the light came in a straight line.
4 When white light passes through a transparent medium (like air) into another (like glass), its components are deflected the first time according to their colour, and once again when they reemerge (back into air, for example). This creates a spread of coloured light rays from red to violet, like the colours of the rainbow. So we observe these seven colors on the screen when a white light is placed in the path of a narrow beam of white light.
This ordered separation of coloured rays is known as the “spectrum”. The spectrum of white light consists of six basic colours arranged in a specific order: red, orange, yellow, green, blue and violet.
P14.3Light and colour AQA GCSE Physics P14 Light Kerboodle Answers: Page No.207
P14.4 Lenses AQA GCSE Physics P14 Light Kerboodle Answers: Page No. 209
- a) A real imageis always inverted whereas a virtual imageis always erect.
- b) A real imageis formed when the rays of light after reflection or refraction actually meet at some point whereas a virtual imageis formed when the rays of light after reflection or refraction appear to meet at a point.
- When the object is a long distance away, the image is formed at the principal focus of the lens. This is because the rays from any point on the object are almost parallel to each other when they reach the lens.
- If the object is moved nearer to the lens towards its principal focus, the screen must be moved further from the lens for you to see a clear image. The nearer the object is to the lens, the larger the image.
P14.5 Using lenses AQA GCSE Physics P14 Light Kerboodle Answers: Page No. 211
2 The image is real.
ii The image formed is Diminished.
iii The image is Inverted.
a ) A convex lens is used as a magnifying glass when the object is placed between the lens and its principal focus the image is formed on the same side of the lens as the object. The image is virtual, upright, and larger than the object. The image can be seen only by looking at it through the lens. This is how a magnifying glass works.
b The image formed is virtual.
ii The image formed is magnified.
iii The image formed is Upright.
c Convex lens is not used as a magnifying glass because the image formed by a concave lens is always virtual, upright, and smaller than the object.
3 A convex lens produces a magnification of x2 when it is used to forma real image that is at a distance of 8.0cm from the object.
a Draw two arrows on the axis of your scale diagram, which are 8 cm apart, one twice as big as the other. Now draw a line from the top of the bigger arrow through the top of the smaller arrow. Where this meets the axis is the position of the lens (this should be 8cm on the other side?) so now complete the ray diagram by drawing a line parallel to the axis from the top of the small arrow to the lens, then to the focal point on the other side. Then extrapolate this back to the top of the large arrow.
b If the object is moved gradually towards the focal point of the lens towards its principal focus, the screen must be moved further from the lens for you to see a clear image. The nearer the object is to the lens, the larger the image and the image is real.
4 a i 
ii The image formed is Real , inverted and the magnification is 1 i.e image is of same size as the object.
b An application for the use of lens is-
In a camera, a convex lens is used to produce a real image of an object on a film (or on an array of pixels for a digital camera). The position of the lens is adjusted to focus the image on the film.
- For a distant object, the distance from the lens to the film must be equal to the focal length of the lens.
- The nearer an object is to the lens, the bigger is the distance from the lens to the film.
Summary questions AQA GCSE Physics P14 Light Kerboodle Answers Page No. 212
i Angle x is angle of incidence and Angle y is angle of reflection,
x = y
ii two correctly reflected rays and normals shown
each reflected ray at same angle to normal as incident ray
image located by tracing two reflected rays back and labelled at correct position
jji The distance from the image to the mirror is same as the distance of the object from the mirror.
b An experiment to test the law of reflection using the ray box and the plane mirror can be described as follows-
draw straight line XY on white paper and use protractor to draw ‘normal’ perpendicular to XY,
place mirror exactly on XY and direct light at point P where normal intersects XY using ray box,
adjust direction of light ray so angle of incidence ≈ 10°, mark direction of incident and reflected rays,
remove mirror and use protractor to measure angles of incidence and reflection,
repeat for different angles of incidence,
record all results in table, results should show angle of incidence = angle of reflection
2 a The figure shows a light ray directed into a rectangular glass block,
i both refractions correct
rays before and after passing through block parallel to each other
ii 
The ray emerging from the block is exactly parallel to the incident ray because-
change in direction at second refraction exactly equal and opposite to change at first refraction,
emerging light parallel to incident light because opposite sides of block parallel
b first refraction towards normal,
2nd refraction away from normal
3 a The difference between specular and diffuse reflection is as follows-
- specular reflection parallel light rays are reflected in a single direction
- diffuse reflection the light is scattered in different directions
a i The type of lens that is shown in this diagram is converging
ii 2 construction rays correct
image correct
b The image is real, inverted and smaller than the object
An application of the lens used in this way is camera.
5 a at least 2 construction rays correct
image correct in correct position
b The image formed is real.
c The magnification produced by the lens is 1.7
6 a at least 2 construction rays correct and image correct
b Determine whether the image is:
i The image is virtual
ii The image is upright
7 a at least 2 construction rays correct
and image correct
b Determine whether the image in a is:
i The image is virtual
ii The image is upright
Practice questions AQA GCSE Physics P14 Light Kerboodle Answers Page No. 213
02.1
correct labels
02.2
When the light is reflected from a smooth surface it is called specular reflection.
When the light is reflectes from a rough surface it is called diffuse reflection.
03.1 2.The range of the angles of incidence used in the investigation is 5–90 degrees (accept 0–90 degrees)
03.2 One way of improving the investigation is to calculate the mean of the results and draw one line
03.3 The name of possible error is systematic error
03.4 The percentage of light reflected changes with the angle of incidence as the angle of incidence increases the % reflection increases but not at a constant rate
04 Figure3 shows a lens, the position of an object, and the position of the image.
04.1 The type of the lens shown is convex lens
04.2 The name of the points F shown on each side of the lens is focal point
04.3
The image shown is
inverted and real.
Disclaimer
Disclaimer: I have tried by level best to provide the answers and video explanations to the best of my knowledge. All the answers and notes are written by me and if there is any similarity in the content then it is purely coincidental. But this is not an alternative to the textbook. You should cover the specification or the textbook thoroughly. This is the quick revision to help you cover the gist of everything. In case you spot any errors then do let us know and we will rectify it. References: BBC Bitesize AQA GCSE Science Kerboodle textbook Wikipedia Wikimedia Commons Join Our Free Facebook Group : Get A* in GCSE and A LEVEL Science and Maths by Mahima Laroyia: https://www.facebook.com/groups/expertguidance.co.uk/ For Free Tips, advice and Maths and Science HelpThis page contains the detailed and easy notes for AQA GCSE Physics Waves for revision and understanding Waves.
AQA GCSE Paper 2: Complete Revision Summary
WAVES
- Transverse and Longitudnal Waves
- Properties of Waves
- Reflection of Waves
- Refractions of Waves
- Sound Waves
- Ultrasound
- Electromagnetic Waves
- Lenses
- BlackBody Radiation
TRANSVERSE AND LONGITUDNAL WAVES
Waves are oscillations or disturbance that transfer energy from one point to another.
TRANSVERSE AND LONGITUDNAL WAVES
TRANSVERSE
LONGITUDNAL
PROPERTIES OF WAVES
Wave Speed
It is the distance travelled
by the wave each second.
Crest
It is the height of the
wave.
Amplitude
It is the maximum displacement
of the wave from the mean
position.
In the example it is 5 m
Frequency
It is the number of waves
passing each second.
It is measured in Hertz (Hz)
F = 1/T 1/4
=0.25H3
Wavelength
The distance between
two consecutive crests
or trough.
Time Period
The time it takes for one
wave to travel.
In the example, one wave
is completed in 4 second.
Trough
It is the depth of the wave.
WAVE SPEED
REFLECTION
- It is the line perpendicular
to the surface where reflection
occurs. - It is the ray incident
on the surface. - Angle of incidence is the
angle between the incident
ray and the normal. - It is the ray which is
reflected from the surface. - Angle of reflection is the angle
between the reflected ray and
the normal.
Reflection is the phenomenon of bouncing
off the wave when it hits a medium.
eq: Reflection of light wave when it hits a plain
mirror.
LAWS OF REFLECTION
a) Incident ray, reflected ray
and normal are in the same
plane.
b) The angle of incidence
is equal to the angle
of reflection.
IMAGE OF A PLANE MIRROR
- It is a virtual image
- Laterally Inverted
- Upright
- The same distance from the source.
| REAL IMAGE | VIRTUAL IMAGE |
| 1. Image can be obtained on a screen. | 1. Image cannot be obtained on a screen |
| 2. The rays actually meet where the image is formed. | 2. The rays happen to meet where the image is formed. |
| eg Images of the cinema |
TYPES OF REFLECTION
REFRACTION
- Bending of light as it travels from one medium to another.
- Light bends because speed of light is different
in different medium. - If the light is travelling from rarer to denser medium then
it bends towards the normal. ∠r < ∠i - If the light is travelling from denser to rarer medium then
it bends away from the normal.∠r > ∠i
The pencil appears to be
broken as the light is
refracted in water.
VISIBLE LIGHT
Visble light is a spectrum of 7 colours VIBGYOR
Each colour has its own freqency and wavelength.
The visible colour of the object will be the colour that is reflected by the object.
Opaque Object
Opaque objects
does not allow the
light to be transmitted
but absorb all
the light.
eg Book,
Translucent Object
These objects
allow some part
of the light to be
transmitted.
eg Plastic
Transparent Object
They allow the
light to be transmitted
through them
without any absorption
eq glass
SOUND WAVES
- They are longitudnal Waves.
- Sound does not travel through a medium.
- Sound requires a medium to travel.
- Sound wave is characterized by compression and
rarefaction. - In sound waves, particles vibrate parallel
to the direction of the wave.
The speed of the sound wave is 330m/s.
Human hearing range
20 Hz to 20,000 Hz
In Echo sounding, high frequency sound waves are sent to determine
the depth or find any object.
The time taken by the sound to come back is noted for the known speed
of sound.
S = vt/2
ULTRASOUND
It is the frequency of sound greater than 20,000 Hz.
ADVANTAGES
- 1. They are non ionizing and
harmless. - 2. They are partially reflected
at the boundaries between
different tissues, so they
can scan even the soft tissues.
USES
1. Used in prenatal scanning.
2. Used to determine the depth of
the sea or the obstacle inside
3. Industrial Imaging .
4. Detecting flaws in metal castings.
water.
USES OF ULTRASOUND
ULTRASOUND SCANNER
Transducer sends ultrasound waves. It crosses
the body and reflected from the tissues. The Transducer
detects the waves reflected from the tissues and the
image is diplayed on the screen in the form of scans.
SONAR
- Ultrasound waves are used to measure
the depth of the sea or find the obstacle
under water. - In SONAR, ultrasound is sent to determine
the depth or find any object. - The time taken by the sound to come back is noted
for the known speed
of sound.
STRUCTURE OF THE EARTH
The crust and the upper mantle cracks and
forms the tectonic plate. The Tectonic
Plates causes Earthquake.
SEISMIC WAVES
- Earthquake takes place
when the rocks or the tectonic
plates in the Earth’s Crust
or the upper Mantle Moves
due to forces inside the Earth. - Seismic Waves are the shock waves
which originate when the forces inside
the earth moves the rocks or
the tecctonic plates. These waves travel
through the Earth and also across its surface. - The Earthquake are detected by Seismometer.
- The focus is the
point from where
the Earthquake
originates. - Seismology is the study of
Seismic Waves. - The nearest point on the surface of the
focus is the epicenter.
SEISMIC WAVES
| P-Wave | S-Wave |
· They are longitudinal · They are faster than · They can travel through · They can pass through | · They are transverse · They are slower than other waves · They travel through · S-waves cannot pass |
- Shadow Zones are the place
where no P and S waves are detected. - S shadow zones where no S wave
and only P waves are detected.
P and S Wave travel through the Mantle
changing directions with depth.
P waves refract at the boundary between mantle and outer core.
S waves being transfer do not travel through liquid outer core.
1. Liquid Outer core under the Mentle.
Shadow zones are detected as P waves refract twice.
Once while entering the core from the mantle
and leaving the core from the mantle. Since
the refraction is further away forming shadow
zones it suggests a liquid outer core under the mantle.
2. Solid Inner Core
Weak P waves in the shadow zones caused by the
refraction of P waves while crossing the boundary
between outer core and inner core.
Long (L-waves) travel the slowest.
They happen only in the Earth’s
crust and they cause more violent
movements.
ELECTROMAGNETIC SPECTRUM
- It is the spectrum with all the
electromagnetic waves arranged
in the order of the increasing wavelength
or frequency. - Electromagnetic waves are electric
and magnetic disturbances that transfer
energy (no matter)
from one point to another. - All the electromagnetic waves travel
with the speed of light-3 x10 8m/s - The frequency and the wavelength can
be given by the formuale :- V = Fλ
ELECTROMAGNETIC SPECTRUM
MNEMONIC
GAMMA RAYS
SOURCE
Gamma rays are produced when
the radiactive substance emit
nuclear radiations.
PROPERTIES
- They have the lowest wavelength.
- They have highest frequency.
- They travel with the speed of light.
USES
1. They are uses to disinfect food
and surgical equipment.
2. It is used to kill cancer cells. In
gamma treatment, the cobalt 60 is
used to direct the gamma radiation to
the cancer cells and kill it without
affecting the surrounding tissue.
DISADVANTAGES
1. Gamma Rays are highly ionizing.
2. Exposure to low dose of Gamma Rays can cause
gene mutation, DNA damage and even cancer.
3. Exposure to high dose of Gamma radiation
can caused killing of the cell.
X-RAYS
SOURCES
They are produced by stopping
high speed electrons.
PROPERTIES
1. They are electromagnetic wave which travels
with the speed of light.
2. They have wavelength greater
than Gamma Rays but smaller than
ultraviolet rays.
3. They have lower frequency than
Gamma Rays but greater than
ultraviolet rays.
4. Their wavelength is about the diameter
of the atom.
USES
1. Shorter wavelength X-rays are
used in X-ray therapy
to kill cancer cells without
destroying the healthy cells.
2. Longer wavelength X-rays are used
to photograph the internal structure
of the body.
DISADVANTAGES
1. X-Rays are highly ionizing
2. Exposure to a low dose of Gamma Rays can cause
gene mutation, DNA damage and even cancer.
3. Exposure to a high dose of Gamma radiation
can caused killing of the cell.
HOW X-RAYS WORK ?
- X-rays are passed through the body.
- The X-rays passes through the soft tissues but are
absorbed by the bones and harder tissues. - The X-rays that pass through the softer areas reach
the detector and appears to be black whereas the
rays that are absorbed do not reach the detector
and appears light in the image. - If any organs containing softer tissues needs to be
photographed then patient is given a contrasting
medium like Barium which becomes a good absorber
of X-rays and helps the photography of that organ. - The detector contains the charged coupled device CCD
which converts X-rays to light which then creates electronic
signal which are used by the computer to make a digital
image.
ULTRA VIOLET RAYS
SOURCE
1. They are produced from the Sun.
The Sun is the source of ultraviolet
rays.
PROPERTIES
1. They are electromagnetic wave which travels
with the speed of light.
2. They have wavelength greater
than X-Rays but smaller than
Violet light.
3. They have lower frequency than
X- Rays but greater than
violet light.
USES
They are uses as fluorescent markers
or fluorescent lamps which contains the
chemical which converts UV Light
to Visible Light.
DISADVANTAGES
1. They can cause sunburn and suntan
2. They can also lead to skin cancer.
3. They can also lead to blindness.
VISIBLE LIGHT
SOURCE
1. Sun and lamps emits light
2. It is the only part of the
specturm which is visible.
PROPERTIES
1. It is made up of 7 colours
2. VIOLET
INDIGO
BLUE
GREEN
YELLOW
ORANGE
RED
3. When the white light is passed
through the prism, it can give the
spectrum of colours.
USES
- Light is used in a camera to take
the picture. - Light is also used in Light Microscope
- Light helps to see the object.
- Light waves are also used in
communication.
DISADVANTAGES
Too much exposure to visible light
can lead to cancer, blindness and
skin damage.
INFRA RED WAVES
SOURCE
- All the hot objects like Kettle, Toaster,
Radiator emits infrared radiation.
PROPERTIES
1. They are electromagnetic wave which
travels
with the speed of light.
2. They have wavelength greater
than visible light but smaller than
Microwaves.
3. They have a lower frequency than visible
light but greater than
microwaves.
USES
1. They are used in optical fibres
for communication.
2. They are used in remote
controls.
3. They are used as infrared
scanners to detect heat produced
by the body and unhealthy
tissues
4. Infrared cameras helps
to see objects in dark.
DISADVANTAGES
1. They can cause sunburn and suntan
2. They can also lead to skin cancer.
3. They can also lead to blindness.
MICROWAVES
The water in the food
absorb microwaves and
become heated and heats the
food preventing the microwave
from heating as it has no water.
SOURCE
- They are emitted as Cosmic Microwave
Background Radiation. Sun also emits
some microwaves.
PROPERTIES
1. They are electromagnetic wave which
travels
with the speed of light.
2. They have wavelength greater
than infrared light but smaller than
Radiowaves.
3. They have a lower frequency than
infrared light but greater than
radiowaves.
4. They are found between Radiowaves
and Infrared Waves.
USES
1. They are used in communication.
2.They are used in satellite TV.
3. They are used in cooking.
4. They are used to carry mobile phone
signal.
DISADVANTAGES
1. Exposure to microwaves can heat
the body tissues.
2. Exposure to high dose of
microwaves can cause eye damage
and even cataract.
RADIOWAVES
SOURCE
Radio waves can be generated by natural sources
such as lightning or astronomical phenomena; or
by artificial sources such as broadcast radio
towers, cell phones, satellites and radar.
PROPERTIES
1. They are electromagnetic wave which
travels
with the speed of light.
2. They have the highest wavelength.
3. They have the lowest frequency.
USES
- They are used in communication
to carry TV, radio and mobile
signals. - They are used in wireless connection
and bluetooth connection.
DISADVANTAGES
1. Exposure to radiowave can heat
the body tissues.
2. Exposure to high dose of
radiowaves can cause eye damage
and even cataract.
LENSES
They are used to refract the light and forms the image of an
objects. They are used in camera.
| CONVEX LENS | CONCAVE LENS |
1. It is a converging lens 2. It is thicker at the center 3. It has a real focus 4. It converges a parallel 5. It is used in microscope, 6. Used to correct short sight | 1. It is a diverging lens. 2. It is thinner at the center 3. It has a virtual focus 4. It diverges a parallel beam 5. Used in some telescopes 6. Used to correct long sight. |
CONCAVE LENS
mages formed is virtual, upright
and smaller than the object.
CONVEX LENS
KEY TERMS
- Waves:- Waves are oscillations or disturbance that
transfer energy from one point to another. - TRANSVERSE WAVES:- In transverse waves, the oscillations move
perpendicular to the direction of the wave. - CRESTS :- It is the height of the wave.
- AMPLITUDE :- It is the maximum displacement
of the wave from the mean
Position. - LONGITUDNAL WAVES :- In longitudnal waves, the oscillations move
parallel to the direction of the wave. - FREQUENCY :- It is the number of waves
passing each second.
It is measured in Hertz (Hz) - WAVE SPEED:- It is the distance travelled
by the wave each second. - TROUGH :- Trough
It is the depth of the wave. - TIME PERIOD :- The time it takes for one
wave to travel. - WAVELENGTH :- The distance between
two consecutive crests
or trough. - REFLECTION :- Reflection is the phenomenon of bouncing
off the wave when it hits a medium.
eq: Reflection of light wave when it hits a plain
Mirror. - REFRACTION :- 1. Bending of light as it travels from one medium to
another.
2. Reflection on a smooth surface.
3. Reflection on a rough surface.
- OPAQUE :- Opaque objects
does not allow the
light to be transmitted
but absorb all
the light. - TRANSLUCENT :- These objects
allow some part
of the light to be
transmitted. - TRANSPARENT :- They allow the
light to be transmitted
through them
without any absorption. - ULTRASOUND:- It is the frequency of sound greater than 20,000
Hz. - EARTHQUAKE:- Earthquake takes place
when the rocks or the tectonic
plates in the Earth’s Crust
or the upper Mantle Moves
due to forces inside the Earth. - SEISMOLOGY:- Seismology is the study of
Seismic Waves. - SEISMIC WAVES:- Seismic Waves are the shock waves
which originate when the forces inside
the earth moves the rocks or
the tecctonic plates. These waves travel
through the Earth and also across its surface. - ELECTROMAGNETIC SPECTRUM:- It is the spectrum with all the
electromagnetic waves arranged
in the order of the increasing wavelength
or frequency. - FOCUS:- Principle
Focus or
Focal points
where the
parallel rays
meet or
appears to meet. - LENS:- They are used to refract the light and forms the
image of an
objects. They are used in camera. - CONVEX LENS:- 1. It is a converging lens.
- CONCAVE LENS:- 1. It is a diverging lens.
- FOCAL LENGTH:- The distance between
the focus and the
center of the lens.
Disclaimer:
I have tried my level best to cover the maximum of your specification. But this is not the alternative to the textbook. You should cover the specification or the textbook thoroughly. This is the quick revision to help you cover the gist of everything. In case you spot any errors then do let us know and we will rectify it.
References:
BBC Bitesize
Wikipedia
Wikimedia Commons
Image Source:
Wikipedia
Wikimedia
Commons
Flickr
Pixabay
Make sure you have watched the above videos and are familiar with the key definations before trying these questions. It is also good to time yourself while doing these questions so that you can work on the speed as well.
