AQA GCSE Physics 32 Light

1
AQA GCSE Physics 3-2Light Sound

• GCSE Physics pages 234 to 251

2
AQA GCSE Specification

• OPTICS
• 13.4 What do mirrors and lenses do to light?
• Using skills, knowledge and understanding of how
  science works
• to construct ray diagrams to show the
  formation of images by plane, convex and concave
  mirrors
• to construct ray diagrams to show the
  formation of images by diverging lenses and
  converging lenses
• to explain the use of a converging lens as a
  magnifying glass and in a camera
• to calculate the magnification produced by a
  lens or mirror using the formula
• magnification image height / object height
• Skills, knowledge and understanding of how
  science works set in the context of
• The normal is a construction-line
  perpendicular to the reflecting/refracting
  surface at the point of incidence.
• The angle of incidence is equal to the angle
  of reflection.
• The nature of an image is defined by its size
  relative to the object, whether it is upright or
  inverted relative to the object and whether it is
  real or virtual.
• The nature of the image produced by a plane
  mirror.
• The nature of the image produced by a convex
  mirror.
• The nature of the image produced by a concave
  mirror for an object placed at different
  distances from the lens.
• Refraction at an interface.
• Refraction by a prism.

• SOUND
• 13.5 What is sound?
• Using skills, knowledge and understanding of how
  science works
• to compare the amplitudes and frequencies of
  sounds from diagrams of oscilloscope traces.
• Skills, knowledge and understanding of how
  science works set in the context of
• Sound is caused by mechanical vibrations and
  travels as a wave.
• Sounds in the range 20-20 000 Hz can be
  detected by the human ear.
• Sound cannot travel through a vacuum.
• The pitch of a note increases as the frequency
  increases.
• The loudness of a note increases as the
  amplitude of the wave increases.
• The quality of a note depends upon the
  waveform.
• Sound waves can be reflected and refracted.
• ULTRASOUND
• 13.6 What is ultrasound and how can it be used?
• Using skills, knowledge and understanding of how
  science works

3
ReflectionNotes questions from pages 234 235

• Explain how convex and concave mirrors differ
  from plane mirrors.
• Copy Figure 2 on page 235 and state what is meant
  by (a) the law of reflection and (b) the normal
  line.
• Copy Figure 1(b) on page 234 and use it to
  explain what is meant by a virtual image.
• What is a real image? Give two examples.
• Copy and answer questions (a), (b) and (c) on
  pages 234 and 235.
• Copy the Key points table on page 235.
• Answer the summary questions on page 235.

4
Reflection ANSWERS

• In text questions
• 1.0 m
• (i) 20o (ii) 40o
• Virtual
• Summary questions

5
Curved mirrors Notes questions from pages 236
237

• By referring to a copy of Figure 2 on page 236
  define what is meant by (a) the principle focus
  and (b) the focal length of a concave mirror.
• Under headings Object beyond principle focus
  and Object between focal point and the mirror
  copy Figures 3 and 4 on page 237 and describe the
  type of image formed in each case.
• Define what is meant by magnification.
• Copy Figure 5a on page 237 and describe the type
  of image formed.
• Copy the Key Points on page 237.
• Copy and answer questions (b) and (c) on pages
  236 and 237.
• Answer the summary questions on page 237.

6
Curved mirrors ANSWERS

• In text questions
• (b) 2.5 (c) Upright, magnified, virtual.
• Summary questions
• 1. (a) Real, inverted, in front. (b) Virtual,
  upright, behind.

(b) The image is virtual, upright and twice as
large as the object.
7
Refraction Notes questions from pages 238 239

• Copy Figure 1 on page 238 and use it to explain
  what is meant by refraction. Also copy the two
  bullet points to the right of Figure 1.
• Copy Figure 2 on page 238 and use it to explain
  the cause of refraction.
• Explain how the speed of light is related to the
  refraction of light.
• draw a diagram and use it to explain why a
  swimming pool appears to be shallower than it
  actually is.
• Explain, with the aid of a diagram, how a prism
  can be used to split white light into its
  component colours. How does this experiment
  indicate that red light travels faster than blue
  light through glass?
• Copy and answer questions (a), (b), (c) and (d)
  on pages 238 and 239.
• Copy the Key points table on page 239.
• Answer the summary questions on page 239.

8
Refraction ANSWERS

• In text questions
• Yes
• The top part moves faster than the lower part of
  the wave so the wave topples over at the top.
• The same.
• (i) Slower (ii) Faster
• Summary questions
• 1. (a) Decreases, towards. (b) Increases, away
  from. (c) Decreases

(b) White light consists of all the colours of
the spectrum. The beam is split into these
colours because each colour is refracted slightly
differently, owing to their different speeds in
glass.
9
Lenses Notes questions from pages 240 241also
uses pages 252 and 253

• Copy the diagram for Exam Style Question 2(a) on
  page 252 and use it to explain what is meant by
  the principle focus is of a converging lens.
• Copy the diagram for Exam Style Question 2(b) on
  page 253 and use it to explain what is meant by
  the principle focus is of a diverging lens.
• For both types of lens define what is meant by
  focal length.
• Describe, with the aid of diagrams, how the image
  formed by a converging lens changes as the
  distance to the object decreases.
• Copy and answer questions (a), (b) and (c) on
  pages 240 and 241.
• Copy the Key points table on page 241.
• Answer the summary questions on page 241.

10
Lenses ANSWERS

• In text questions
• A 5 cm focal length lens
• Inverted
• To make it appear much larger so any flaws can be
  seen.

• Summary questions
• (a) Converging, real.
• (b) Diverging, virtual.
• 2. (a) Upright, enlarged and virtual.
• (b) (i) Inverted, enlarged and virtual.
• (ii) The slide must be moved towards the
  screen.
• (c) The image real, inverted and enlarged.
  Magnification 3.

11
Using lenses Notes questions from pages 242 243

• Copy Figure 1 on page 242 with all of the labels
  and explain the rules for drawing the three rays
  shown.
• Draw Figure 2 on page 242 and explain how the
  lens of a camera has to be adjusted to cope with
  a range of object distances.
• Explain with the aid of Figure 3 on page 243 how
  a magnifying glass produces an image.
• Explain with the aid of Figure 4 on page 243 how
  a concave lens produces an image.
• Copy and answer questions (a), (b), (c) and (d)
  on pages 242 and 243.
• Copy the Key points table on page 243.
• Answer the summary questions on page 243.

12
Using lenses ANSWERS
Summary questions

• In text questions

(b) Towards the object. (c) To inspect objects in
detail. (d) The image is always smaller than the
object.
13
Sound Notes questions from pages 244 245

• (a) What type of objects produce sound waves? (b)
  What is the typical range of frequencies audible
  to a young person? (c) How does this range change
  with age?
• Draw a diagram and describe an experiment to show
  that sound waves do not travel through a vacuum.
• Draw Figure 1 on page 244 and explain the
  difference between longitudinal and transverse
  waves. State which type is sound.
• (a) What is an echo? (b) How are echoes affected
  by the surface of materials?
• Why does sound travel better at night?
• Copy and answer questions (a), (b), (c), (d) and
  (e) on pages 244 and 245.
• Copy the Key points table on page 245.
• Answer the summary questions on page 245.

14
Sound ANSWERS

• In text questions
• A mouse.
• The sound becoming audible again.
• Wave one end from side to side.
• There are no reflections, so each note dies away
  more quickly outdoors.
• Colder.

• Summary questions
• (a) Reflected.
• (b) Scattered, absorbed.
• (c) Refracted.
• 2. (a) About 18000 Hz
• (b) The vibrating surface of the loudspeaker
  pushes the air near it to and fro, creating sound
  waves which spread out from the loudspeaker.
• (c) The ball inside goes around at constant
  speed and makes the surrounding air vibrate.

15
Musical sounds Notes questions from pages 246
247

• Explain the difference between a musical note and
  noise.
• Draw wave diagrams to explain what happens when
  there is an increase in a sound waves (a)
  loudness and (b) pitch.
• Copy and answer questions (a), (b) and (c) on
  pages 246 and 247.
• Explain how the three main categories of musical
  instrument produce sound.
• Why do different musical instruments producing
  the same note sound different from each other?
  Illustrate your answer with a waveform diagram.
• Copy the Key points table on page 247.
• Answer the summary questions on page 247.

16
Musical sounds ANSWERS

• In text questions
• An ambulance, a police vehicle, a fire engine, an
  ice cream van.
• The waves are not as tall.
• The waves would be smaller in height and
  stretched out more.

• Summary questions
• 1. (a) The waves would be taller but would have
  the same spacing.
• (b) The waves would be more stretched out but
  would have the same height.
• 2. (a) (i) The note has a higher pitch
  (frequency).
• (ii) The note has a higher pitch (frequency).
• (b) The sound of a violin (played correctly)
  lasts as long as the violin bow is in contact
  with a string. The sound of a drum dies away
  after the drum skin has been struck. A drum note
  is less rhythmical than a violin note.

17
Ultrasound Notes questions from pages 248 249

• What is ultrasound? State a frequency as part of
  your answer.
• Copy and answer question (a) on page 248.
• (a) Describe how ultrasound is used to obtain
  pre-natal scans. (b) What are the advantages of
  ultrasound scans over X-ray imaging?
• How is ultrasound used in cleaning?
• Draw the diagram shown in summary question 2 and
  explain how ultrasound can be used to detect
  flaws inside solid objects.
• Copy and answer question (b) on page 249.
• Copy the Key points table on page 249.
• Answer the summary questions on page 249.

18
Ultrasound ANSWERS

• In text questions
• The material absorbs some of the ultrasonic sound
  from the loudspeaker.
• They do not vibrate fast enough.
• 30 mm from the transmitter.

• Summary questions
• 1. (a) The organs have a different density to
  the surrounding tissue. So ultrasound is
  reflected at the tissue/organ boundaries.
• (b) Ultrasound is not ionising radiation
  whereas X-rays are. Ionising radiation is harmful
  to living tissue. Ultrasound is reflected at the
  boundaries between different types of tissue,
  whereas X-rays are not.
• 2. (a) Two.
• (b) 32-34 mm and 50 mm.

19
Light and sound issues Notes questions from
pages 250 251

• Answer questions 1(a), 2(a) and 2(b) on page 250.
• Answer questions 3(a) and 3(b) and on page 251.

20
Light and sound issues ANSWERS

• (a) Air pollution due to dust particles, microbes
  in the air if hose equipment is not clean.
• (a) To make sure the test is a fair comparison of
  the different materials.
• (b) Cushion fabric is the best absorber, soft
  wallpaper is next and plaster board is next. wood
  panel reflects sound waves more than plaster
  board does.
• (a) About 166 hours.
• (b) The data is permanently stored on the disc.

21
How Science Works ANSWERS

• Either greater accuracy or precision.
• Millimetres
• The range of the dependent variable was 1.492 to
  1.548.
• The mean of the dependent variable was 1.5206
  reasonably 1.52.
• Jenny was using crown glass.