Listening to music on a mobile phone can be great, but sometimes it just isn't quite loud enough! That's when you need a passive sound amplifier...
The speaker in your phone is an active sound amplifier, it needs electricity from the battery to make it work. A passive sound amplifier doesn't need a power source.
Have you ever rolled up a sheet of paper into a cone shape and talked through it? Try it and see what happens. You should notice your voice sounds a bit louder, just because the sound is travelling through a cone? Can you work out why?
This week's challenge is to use everyday materials and a smart phone to create a passive amplifier to make the music from the phone sound louder. (Disclaimer - I am only promising the sound could be made louder, the quality of the sound will almost certainly get worse!)
You will need to consider the material you choose to use. Would it be better to have a smooth surface or a rough surface for the sound to travel past?
You will also need to think about the shape of your amplifier, will it need to be a cone shape or would a tube work better?
Here are some examples that other people have tried to get you thinking...
Some work better than others. Can you predict which ones might be best?