11.1) Write down whether each of the following statements about sound is true or false.
a: Sounds are produced by sources which vibrate.
b: Sounds are carried by air which moves from the source to our ears.
c: The frequency of a sound is the number of vibrations cach second.
d: A sound with a higher frequency is louder than one with a lower frequency.
e: Sound can travel through solids, liquids and gases.
f: Sound can travel through a vacuum.
g Sound waves travelling down the car canal push on the cochlea.

11.2) Loudspeaker A vibrates 200 times cach second. Loudspeaker B vibrates 400 times each second.
a: What is the frequency of the sound produced by loudspeaker A?
Give the value and the unit.
b: Which loudspeaker produces the note with the lower pitch?
c: A ruler vibrates 70 times in 20 seconds. What is the frequency of its vibration?

11.3) The diagram below shows a trace which represents a sound wave.

Copy the trace.
a: On your copy, mark the amplitude of the wave.
b: Add a second trace to show a wave which has the same amplitude as the wave shown but a higher frequency.

11.4) The trace below represents a sound wave which is changing.

a: State whether the frequency of the wave is increasing, decreasing or staying the same.
b: State whether the pitch of the sound is increasing, decreasing or staying the same.
c: State whether the loudness of the wave is increasing, decreasing or staying the same. Explain your answer.