Light And Sound
Overview
Light lets you see the world, and sound lets you hear it, but both travel as waves, and both obey the same core rules when they bounce off surfaces or pass from one material into another. Understanding reflection, refraction and total internal reflection unlocks everything from fibre-optic broadband to the sparkle of a diamond.
In this topic you will apply the law of reflection, use Snell's law to calculate refractive index, find critical angles, and draw accurate ray diagrams. You will also explore how sound travels, how an oscilloscope reveals its frequency and amplitude, and why pitch and loudness depend on different wave properties.
Objectives
- Know that light waves are transverse waves and that they can be reflected and refracted
- Use the law of reflection (the angle of incidence equals the angle of reflection)
- Draw ray diagrams to illustrate reflection and refraction
- Investigate the refraction of light, using rectangular blocks, semi-circular blocks and triangular prisms
- Know and use the relationship between refractive index, angle of incidence and angle of refraction: n = sin i / sin r
- Investigate the refractive index of glass, using a glass block
- Describe the role of total internal reflection in transmitting information along optical fibres and in prisms
- Explain the meaning of critical angle c
- Know and use the relationship between critical angle and refractive index: sin c = 1 / n
- Know that sound waves are longitudinal waves that can be reflected and refracted
- Know that the frequency range for human hearing is 20-20,000 Hz
- Investigate the speed of sound in air
- Understand how an oscilloscope and microphone can be used to display a sound wave
- Investigate the frequency of a sound wave using an oscilloscope
- Understand how the pitch of a sound relates to the frequency of vibration of the source
- Understand how the loudness of a sound relates to the amplitude of vibration of the source
Lesson Note
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Lesson Evaluation
Congratulations on completing the lesson on Light And Sound. Now that youve explored the key concepts and ideas, its time to put your knowledge to the test. This section offers a variety of practice questions designed to reinforce your understanding and help you gauge your grasp of the material.
You will encounter a mix of question types, including multiple-choice questions, short answer questions, and essay questions. Each question is thoughtfully crafted to assess different aspects of your knowledge and critical thinking skills.
Use this evaluation section as an opportunity to reinforce your understanding of the topic and to identify any areas where you may need additional study. Don't be discouraged by any challenges you encounter; instead, view them as opportunities for growth and improvement.
- When a ray of light passes from air into glass, it bends: A) Away from the normal B) Towards the normal C) Along the normal D) It does not change direction Answer: B
- The critical angle of a material with a refractive index of 1.4 is: A) 35.3 degrees B) 41.8 degrees C) 45.6 degrees D) 48.6 degrees Answer: C
- Sound waves are: A) Transverse waves that can travel through a vacuum B) Longitudinal waves that can travel through a vacuum C) Transverse waves that need a medium D) Longitudinal waves that need a medium Answer: D
- The frequency range of human hearing is: A) 2 Hz to 2000 Hz B) 20 Hz to 20 000 Hz C) 200 Hz to 200 000 Hz D) 2000 Hz to 20 000 Hz Answer: B
- On an oscilloscope trace, a louder sound would show: A) More waves on the screen B) Fewer waves on the screen C) Taller waves D) Shorter wavelength Answer: C
Available on the Green Bridge App
Download the Green Bridge CBT app on your phone or computer to access full lesson notes, practice questions, and more.
Available on the Green Bridge App
Download the Green Bridge CBT app on your phone or computer to access full lesson notes, practice questions, and more.
Recommended Books
Practice Mock Questions
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