Sound

In the back of your books answer the following questions: Mini Test In the back of your books answer the following questions: What is the speed of light in m/s? (1 mark) 2. If you look at a magenta t-shirt through a green filter what colour will it look? (1 mark) 3. Draw a diagram that represents the Law of Reflection (6 marks) 4. Which has the longer wavelength, infrared or microwave. Give a use of both. (3 marks) 5. State the definition of a longitudinal wave (2 marks)

Answers What is the speed of light in m/s? (1 mark) 300,000,000 m/s or 3 x 108 m/s

Answers 2. If you look at a magenta t-shirt through a green filter what colour will it look? (1 mark) It will look black. Magenta is a secondary colour made of red and blue. A green filter only allows green light through therefore none of the magenta (red and blue) light ill get through. The shirt will look black.

Answers 3. Draw a diagram that represents the Law of Reflection (6 marks) Incident Ray Reflected Ray i r

Microwave has the longer wavelength Answers 4. Which has the longer wavelength, infrared or microwave. Give a use of both. (3 marks) Microwave has the longer wavelength Microwave: cooking food / mobile phone communications Infrared: remote controls/ thermal imaging

Answers 5. State the definition of a longitudinal wave (2 marks) A longitudinal wave has oscillations parallel to the direction of energy transfer.

Sound

Why do we see lightning before we hear the thunder? Sound Why do we see lightning before we hear the thunder?

By the end of this lesson: Sound By the end of this lesson: You will have carried out and be able to describe an experiment to determine the speed of sound

Experiment

Results Time taken to hear echo: Distance sound wave has travelled: speed = distance/time :

The speed of sound is 330 m/s In groups discuss why your experimental result differs from the above value.