A small electronic speaker with an active flashing LED indicator is suspended inside a sealed glass dome. The dome is connected to a vacuum pump.
The speaker is playing a continuous tone and the LED is flashing. The vacuum pump is switched on and extracts all the air from the dome. State what observers see and what they hear after the air has been removed.
State what this demonstration shows about how light waves and sound waves travel.
Describe how the speaker cone produces sound waves before the air has been removed.
State the typical lower and upper frequency limits of human hearing, including units.
295 exam-style questions on CIE IGCSE Physics Sound, covering Sound. Each one has a worked solution and a mark scheme showing where the marks go.