Science labs › Physics › Radio Mast to House
Send radio waves across town. How fast do they arrive, and why is the far house quieter?
Radio Mast to House lab · Last updated: 16 October 2026
You send radio waves from a mast across a town and watch them reach the houses. They find out how fast the waves travel and why the house furthest away hears a quieter signal. Radio waves carry music, phone calls and Wi-Fi, so this is the science inside everyday gadgets.
What you'll discover
- Radio waves are a kind of light our eyes cannot see, and they travel at the speed of light.
- A signal spreads out as it travels, so the same energy covers a bigger area and gets weaker with distance.
- Buildings and hills can absorb or block some of the signal, making reception worse in places.
The science in plain words
Radio waves are electromagnetic waves, the same family as visible light, microwaves and X-rays, but with much longer wavelengths, from millimetres to kilometres. A radio transmitter makes them by sending a rapidly changing electric current up and down an antenna, so the changing electric and magnetic fields spread outwards.
Like all electromagnetic waves, radio waves travel at the speed of light, about 300,000 kilometres per second. That is fast enough to cross a town in a tiny fraction of a millisecond, so to us the signal arrives at every house at once. Radio waves need no air or wire to travel, which is how we talk to spacecraft.
The far house gets a weaker signal because the wave spreads out. A mast sends energy in many directions, so the further the wave travels, the larger the area that energy is spread over. For waves spreading out evenly in all directions, doubling the distance leaves only a quarter of the strength. This is called the inverse square law. Buildings, trees and hills also absorb and reflect part of the signal. A radio receiver picks up the faint wave with its own antenna and amplifies it, but if the signal is too weak, noise drowns it out and the sound becomes crackly.
Where it fits
- India, NCERT: Goes beyond the NCERT syllabus for classes 6 to 10; it builds on Class 9 Sound for waves and Class 10 light chapters.
- United States: Grades 6 to 12
- Next Generation Science Standards: MS-PS4-2, HS-PS4-5
Common questions
How fast do radio waves travel?
Radio waves travel at the speed of light, about 300,000 kilometres per second in empty space and only very slightly slower in air. A radio signal could go round the Earth more than seven times in one second, so across a town it arrives almost instantly.
Why does radio signal get weaker further from the mast?
The wave spreads out as it travels, so its energy is shared over a larger and larger area. If it spreads out evenly, doubling the distance cuts the strength to a quarter. Buildings, hills and trees also absorb or reflect some of the signal on the way.
Are radio waves the same as sound waves?
No. Sound is a vibration of air or another material and travels at about 340 metres per second. Radio waves are electromagnetic waves that need no material and travel at the speed of light. A radio turns the radio wave back into sound using a speaker.
Related labs
- Rainbow and Beyond: Slide from ultraviolet through the rainbow to infrared. Which light makes the star glow?
- Wave Motion: Shake one end of a cord. How fast does the wave run, and how long is each wave?
- Sound Waves: A speaker squeezes the air. Watch the squeezes march across the stage.
See all physics labs or every Taz science lab.
Try it yourself
The Radio Mast to House lab is one of the interactive 3D science labs inside Taz. Change one thing, predict what will happen, then run it and watch. Labs open after you sign in.