PHYSICS

Part III: Waves

Hong Kong Diploma of Secondary Education

(HKDSE)

Notes & Exercises

Chapter 13 to 18

ANDY WONG S.T.

2

TABLE OF CONTENTS

CHAPTER 13 WAVE MOTION ...................................................................................................... 5

1. Nature of waves ........................................................................................... 5

2. Mechanical and electromagnetic waves .................................................. 5

3. Transverse and longitudinal waves ........................................................... 5

4. Physical terms describing a wave ............................................................. 5

5. Huygens’ Principle** .................................................................................... 5

6. Graphical representation of travelling waves .......................................... 5

7. Speed of propagation of mechanical waves ............................................ 5

8. Intensity of wave energy ............................................................................. 5

CHAPTER 14 WAVE PHENOMENA .............................................................................................. 7

1. Reflection of waves ...................................................................................... 7

2. Phase change on reflection ........................................................................ 7

3. Applications of wave reflection................................................................... 7

4. Refraction of waves ..................................................................................... 7

5. Diffraction of waves ..................................................................................... 7

6. Principle of superposition ............................................................................ 7

7. Interference of waves .................................................................................. 8

8. Polarization of waves** ............................................................................... 8

CHAPTER 15 LIGHT AS WAVES ................................................................................................. 9

1. Electromagnetic spectrum .......................................................................... 9

2. Wave nature of light ..................................................................................... 9

3. Observation of interference of light ........................................................... 9

4. Production of coherent sources ................................................................. 9

5. Young’s double slit experiment .................................................................. 9

6. Measurement of wavelength in Young’s experiment* ............................ 9

7. Appearance of fringes in Young’s experiment ........................................ 9

8. Alternative methods to produce Young’s fringes .................................... 9

9. Diffraction by a single slit .......................................................................... 10

10. Explanation of diffraction by Huygens’ Principle* ................................. 10

11. Diffraction pattern under direct observation ........................................... 10

12. Diffraction grating* ..................................................................................... 10

13. White light incidence* ................................................................................ 10

14. Measurement of wavelength by diffraction grating* ............................. 10

CHARTER 16 GEOMETRIC OPTICS ........................................................................................... 11

1. Laws of reflection ....................................................................................... 11

2. Explanation of reflection by Huygens’ Principle** ................................. 11

3. Images formed by plane mirror ................................................................ 11

4. Laws of refraction ....................................................................................... 11

5. Definition of refractive index ..................................................................... 11

Part III

3

6. Refraction of light through a prism .......................................................... 11

7. Dispersion ................................................................................................... 11

8. Light entering from a denser into a less dense region ......................... 11

9. Critical angle and total internal reflection ............................................... 12

10. Lenses ......................................................................................................... 12

11. Real and virtual images............................................................................. 12

12. Graphical representation of images formed by lens ............................. 12

13. Magnification of lens .................................................................................. 12

14. Lens equation* ............................................................................................ 12

15. Relationship between u and v for convex (converging) lens .............. 12

16. Relationship between u and v for concave (diverging) lens ................ 12

17. Two thins lenses in contact ...................................................................... 13

18. Visual angle................................................................................................. 13

19. Angular magnification ................................................................................ 13

20. Magnifying glass......................................................................................... 13

21. Microscope – normal adjustment ............................................................ 13

22. Telescope – normal adjustment............................................................... 13

23. Eye-ring (exit pupil)** ................................................................................. 13

24. Grating spectrometer** .............................................................................. 14

CHAPTER 17 SOUND ................................................................................................................ 15

1. Wave nature of sound ............................................................................... 15

2. Measurement of speed of sound by Kundt’s tube** ............................. 15

3. Comparison of sound waves and light waves ....................................... 15

4. Intensity of sound waves .......................................................................... 15

5. Sound intensity level (loudness) .............................................................. 15

6. Loudness of two different sounds ............................................................ 15

7. Audible frequency range ........................................................................... 15

8. Ultrasound ................................................................................................... 15

9. Pitch of sound ............................................................................................. 15

10. Quality of sound ......................................................................................... 15

11. Noise ............................................................................................................ 16

12. Absorption of sound and sound proofing ............................................... 16

CHAPTER 18 STATIONARY WAVES .......................................................................................... 17

1. Formation of stationary waves ................................................................. 17

2. Properties of stationary waves ................................................................. 17

3. Graphical representation of stationary waves ....................................... 17

4. Difference between travelling waves and stationary waves ................ 17

5. Vibration of a stretched string .................................................................. 17

6. Overtones of a vibrating string ................................................................. 17

7. Differences between plucking and vibrator ............................................ 17

8. Travelling and stationary sound waves** ............................................... 17

9. Vibration of air column** ........................................................................... 17

**APPENDIX II INTERFERENCE AND POLARIZATION OF LIGHT ................................................. 19

4

1. Optical path ................................................................................................. 19

2. Interference pattern formed by an air wedge......................................... 19

3. Newton’s rings ............................................................................................ 19

4. Interference pattern formed by a uniform thin film ................................ 19

5. Blooming of glass surface – non-reflecting glass ................................. 19

6. Polarization of light by Polaroid – selective absorption ........................ 19

7. Polarization of light by reflection .............................................................. 20

8. Polarization of light by scattering ............................................................. 20

9. Applications of polarization ....................................................................... 20

*These topics are not required in physics part of HKDSE Combined Science curriculum.

Part III

5

CHAPTER 13

WAVE MOTION

[ch24]

1. Nature of waves

2. Mechanical and electromagnetic waves

3. Transverse and longitudinal waves

4. Physical terms describing a wave

5. Huygens’ Principle**

6. Graphical representation of travelling waves

7. Speed of propagation of mechanical waves

Factors affecting speed of propagation of waves

8. Intensity of wave energy

6

Part III

7

CHAPTER 14

WAVE PHENOMENA

[ch25]

1. Reflection of waves

Reflection at plane barrier/reflector/surface

2. Phase change on reflection

3. Applications of wave reflection

4. Refraction of waves

Refraction at a plane boundary

[Ch 24.9 (explained by Huygens’ Principle)]

Refractive index

Refraction of microwave

5. Diffraction of waves

6. Principle of superposition

(ch24)

8

7. Interference of waves

Constructive or destructive waves

Interference pattern

Interference of microwaves

8. Polarization of waves**

e.g. EM waves

Part III

9

CHAPTER 15

LIGHT AS WAVES

[ch26, 27]

1. Electromagnetic spectrum

(ch28.1)

2. Wave nature of light

3. Observation of interference of light

4. Production of coherent sources

5. Young’s double slit experiment

Conditions for fringes

6. Measurement of wavelength in Young’s experiment*

7. Appearance of fringes in Young’s experiment

8. Alternative methods to produce Young’s fringes

Fresnel’s biprism

Lloyd’s mirror

10

9. Diffraction by a single slit

(ch.27.1)

10. Explanation of diffraction by Huygens’ Principle*

11. Diffraction pattern under direct observation

(ch27.6)

12. Diffraction grating*

(ch27.3)

13. White light incidence*

14. Measurement of wavelength by diffraction grating*

Part III

11

CHARTER 16

GEOMETRIC OPTICS

[ch32]

1. Laws of reflection

2. Explanation of reflection by Huygens’ Principle**

(ch24.8)

3. Images formed by plane mirror

4. Laws of refraction

5. Definition of refractive index

6. Refraction of light through a prism

7. Dispersion

(ch24.12)

8. Light entering from a denser into a less dense region

(ch24 .10)

12

9. Critical angle and total internal reflection

(ch24.11)

10. Lenses

11. Real and virtual images

(ch32.7)

12. Graphical representation of images formed by lens

13. Magnification of lens

(ch32.8)

14. Lens equation*

(ch32.4)

15. Relationship between u and v for convex (converging) lens

16. Relationship between u and v for concave (diverging) lens

Part III

13

17. Two thins lenses in contact

(ch32.9)

18. Visual angle

19. Angular magnification

20. Magnifying glass

Comparison for images set at near point and at far point

Limitations

21. Microscope – normal adjustment

22. Telescope – normal adjustment

Disadvantages of refracting telescope

23. Eye-ring (exit pupil)**

14

24. Grating spectrometer**

Part III

15

CHAPTER 17

SOUND

[ch30]

1. Wave nature of sound

2. Measurement of speed of sound by Kundt’s tube**

3. Comparison of sound waves and light waves

4. Intensity of sound waves

5. Sound intensity level (loudness)

6. Loudness of two different sounds

7. Audible frequency range

8. Ultrasound

9. Pitch of sound

10. Quality of sound

(ch29.13)

16

11. Noise

12. Absorption of sound and sound proofing

Part III

17

CHAPTER 18

STATIONARY WAVES

1. Formation of stationary waves

2. Properties of stationary waves

3. Graphical representation of stationary waves

4. Difference between travelling waves and stationary waves

5. Vibration of a stretched string

6. Overtones of a vibrating string

7. Differences between plucking and vibrator

8. Travelling and stationary sound waves**

9. Vibration of air column**

In open tube

18

In closed tube

Part III

19

**APPENDIX II

INTERFERENCE AND POLARIZATION OF LIGHT

1. Optical path

(ch26.7)

2. Interference pattern formed by an air wedge

(ch26 .10)

Spacing of fringes in air wedge

(ch26 .11)

3. Newton’s rings

(ch26 .12)

Overlapping of Newton’s rings

Radius of Newton’s rings

4. Interference pattern formed by a uniform thin film

(ch26 .15)

A thin film with a large surface area

5. Blooming of glass surface – non-reflecting glass

(ch26.16)

6. Polarization of light by Polaroid – selective absorption

(ch28)

20

7. Polarization of light by reflection

8. Polarization of light by scattering

Colour of sunrise and sunset

9. Applications of polarization

(ch28)