Sound

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[|Scream in space]
 * Differences of light and sound(Questions to think of) ||
 * 1.Which is fastest, light or sound?

2.How does sound travel?

3.Which material does sound travel fastest in, solids, liquids or gases?

4.Why does it travel fastest in your answer to q3?

5.What is ultrasound and what are 2 uses of ultrasound? Check the uses from [|howstuffworks.com] ||
 * Ultrasound** is a sound wave with a frequency greater than the human hearing range.

The vibrations of longitudinal waves are in the same direction as the wave. This is how sound waves move. When a sound wave travels through air, the particles are first pushed together or **compressed** and then spread apart or **rarefied**. These areas are called **compressions** and **rarefactions**. ||
 * Light and sound waves are both forms of energy. There are two ways that energy can travel in waves; by **longitudinal** or **transverse** waves.

DIFFERENT OPTIONS FOR INVESTIGATING SOUND: youtube video clips [|Standing waves in tube open at one end] (resonance tube) [|Using an oscilloscope and microphones] ​ [|Speed of sound through different mediums] [|Using a camera] (large distance) - this example also focusses on speed of sound variation with temperature [|Using echoes] (large distance) [|Using echoes] (Audacity software)

Investigate/research uses of ultrasound and or how animals use sound

TASK 24th Sep. Wednesday (October holiday homework due by Monday 6th Oct.)
Create a news article using your text and laptop. Work individually or in pairs to produce the article to explain the following: Include articles, pictures and diagrams to answer the questions below: •How does sound travel? •What does frequency tell us about sound? •A diagram of a high frequency and a low frequency sound •What does ‘hearing range’ mean? •What is volume measured in and what is another word for volume? •How does the sound get converted to electrical signals in the brain? •Why would you hear higher frequencies than an adult? Frequency range of human hearing ( 20 ~ 20,000 Hz ) || **Reflection** Sound reflects back as an echo if the sound wave hits a barrier.
 * “Humans can only hear certain frequencies of birdsong”**
 * **Animal** || **Frequencies they can make (Hz)** || **Frequencies they can hear (Hz)** ||
 * cat || 750 – 1600 || 60 – 65000 ||
 * dog || 450 – 1000 || 15 – 50000 ||
 * robin || 2000 – 13000 || 250 – 21000 ||
 * human || 80 – 4100 || 20 – 20000
 * grasshopper || 7000 – 10000 || 100 – 15000 ||
 * bat || 10000 – 120000 || 1000 – 120000 ||

**Refraction** Sound refracts when it passes from warm air into cold air. e.g. still night (warm morning) sounds carry well

**Diffraction and interference** Sound spreads out when passing through small opening, around obstacles and through doorways.

The properties of sound in terms of movement of air particles. //__Check your understanding__//

Light does not need __ a substance/medium __to move through. Light is a __ transverse __wave. The vibrations are at __ right angles __ to the direction the wave is moving.
 * 1** **What is the difference between longitudinal and transverse waves?**

[|Image from www.pinterest.com] __ Longitudinal __waves Radio waves, X-rays, ultraviolet light __ Longitudinal __waves
 * 2 Draw and label each wave type and say which represents a light wave and which a sound wave.**
 * 3 What sort of wave is produced when air particles are compressed and rarefied?**
 * 4 Give three examples of transverse waves.**
 * 5 What type of wave is a sound wave?**

Recognise the link between loudness and amplitude, pitch and frequency, using an oscilloscope.

**What do you know about Sound waves?**
1. A string that vibrates quickly makes __ high frequency __. 2. We see lightning before we hear thunder. It means sound waves travel __ slower __ than light waves. 3. Plucking a string harder makes the sound __ louder __ as its __ amplitude __ is __ greater __. 4. Plucking a string softly makes the sound __ quieter __ as its __ amplitude __ is smaller. 5. A reflected sound is called __ echo __. 6. The part of the ear that detects sound is called 7. The speed of sound in the air is __ 330ms-1 __ Answer the questions below. Which part of a wave represents volume? Which part of a wave represents pitch? See diagrams. Choose which wave has the highest pitch. Then choose which wave has the loudest volume. **Amplitude of sound is related to the loudness of a sound.** **Frequency: Frequency of sound waves makes different pitches**. e.g. high frequency = high note

[|Sound revision] from what2learn.com: Play the sound and hearing game.


 * **Material** || **Speed of sound in m/s** ||
 * steel || 6000 ||
 * aluminium || 5100 ||
 * iron || 5000 ||
 * concrete || 5000 ||
 * glass || 4500 ||
 * copper || 3700 ||
 * brick || 3000 ||
 * salt water || 1560 ||
 * water || 1500 ||
 * mercury || 1450 ||
 * ethanol || 1200 ||
 * air || 330 ||
 * oxygen || 316 ||
 * carbon dioxide || 260 ||

relate sound to hearing and the structure of the ear Image from [|www.directhearingaids.co.uk] Visit the website above and find the functions of the Cochlea, Eustachian tube and Semicircular canals.

Practice questions and answers ( 7th Oct. 2014)