Page 149 - Knowledge Organiser Yr7 24-25

Knowledge Base: Science 7.13 Sound Year 7
5. Echoes
5.1
What is an echo?
An echo is produced when sound is reflected off a surface.
5.2
What is the speed of sound at normal room temperature?
340m/s.
5.3
Give an example of an animal that can use echoes to map their surroundings.
Bats.
Worked example question:
Calculate how far away a wall is from you if it takes 20 seconds to hear an echo.
6. Detecting Sound
6.4
What does the ear drum do when a sound wave hits it?
It vibrates.
6.5
What is the cochlea?
A snail-like structure filled with tiny hairs and liquid.
6.6
What is the function of the specialised cells at the bottom of the hairs inside the cochlea?
They transfer the movement to electrical signals which can then be sent via the auditory nerve to the brain.
6.7
What part of the human ear is similar to the diaphragm of a microphone?
The ear drum.
6.8
Vibrations of the diaphragm of a microphone are turned into electrical signals. What part of the human ear is this similar to?
The hairs in the cochlea.
7. Ultrasound
7.1
What is ultrasound?
A sound with a frequency of over 20,000Hz.
7.2
Why can humans not detect this sound?
Because it is above the range of human hearing.
7.3
Name two ways in which we can use ultrasound for detection.
1. To make images of an unborn baby. 2. To look at shipwrecks at the bottom
of the sea.
7.4
Why is it safe to use ultrasound on an unborn baby?
Because it is a sound wave and these are not harmful.
6. Detecting Sound
6.1
What part of the human body is used to detect sound?
The ear.
6.2
What are the labels for 1-8?
1 – pinna
2 – ear canal
3 – ear drum
4 – hammer
5 – anvil
6 – stirrup
7 – cochlea
8 – auditory nerve
6.3
Which two parts of the ear make up the outer ear?
The pinna and the ear canal.
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