Let's start with the lowest-frequency waves: bonesgamma raysInfra redLightlongestmicrowavesPIRradio wavesradiotherapyshortestsoft tissuespeed camerasthermal imagingultra violetvacuumwavelengthX-rays[?]. These have the bonesgamma raysInfra redLightlongestmicrowavesPIRradio wavesradiotherapyshortestsoft tissuespeed camerasthermal imagingultra violetvacuumwavelengthX-rays[?] wavelength of all the waves in the EM spectrum.

Next come bonesgamma raysInfra redLightlongestmicrowavesPIRradio wavesradiotherapyshortestsoft tissuespeed camerasthermal imagingultra violetvacuumwavelengthX-rays[?]. As well as for mobile phones, they are used for bonesgamma raysInfra redLightlongestmicrowavesPIRradio wavesradiotherapyshortestsoft tissuespeed camerasthermal imagingultra violetvacuumwavelengthX-rays[?]. They have a bonesgamma raysInfra redLightlongestmicrowavesPIRradio wavesradiotherapyshortestsoft tissuespeed camerasthermal imagingultra violetvacuumwavelengthX-rays[?] of a few centimetres.

Next are the waves that we feel as heat: bonesgamma raysInfra redLightlongestmicrowavesPIRradio wavesradiotherapyshortestsoft tissuespeed camerasthermal imagingultra violetvacuumwavelengthX-rays[?] waves. "bonesgamma raysInfra redLightlongestmicrowavesPIRradio wavesradiotherapyshortestsoft tissuespeed camerasthermal imagingultra violetvacuumwavelengthX-rays[?]" detectors pick up these waves if someone approaches, and will trigger a security light or a burglar alarm. Emergency services may use bonesgamma raysInfra redLightlongestmicrowavesPIRradio wavesradiotherapyshortestsoft tissuespeed camerasthermal imagingultra violetvacuumwavelengthX-rays[?] cameras to reveal where casualties may be stuck under rubble.

bonesgamma raysInfra redLightlongestmicrowavesPIRradio wavesradiotherapyshortestsoft tissuespeed camerasthermal imagingultra violetvacuumwavelengthX-rays[?] is the only part of the electromagnetic spectrum that we can see directly. It travels at 300 million metres per second - but then again so do all the other EM waves. Also, all EM waves can cross a bonesgamma raysInfra redLightlongestmicrowavesPIRradio wavesradiotherapyshortestsoft tissuespeed camerasthermal imagingultra violetvacuumwavelengthX-rays[?].

"Blacklights" aren't really black - they give off bonesgamma raysInfra redLightlongestmicrowavesPIRradio wavesradiotherapyshortestsoft tissuespeed camerasthermal imagingultra violetvacuumwavelengthX-rays[?] waves that our eyes can't see, but they make some substances fluoresce (glow).

Wilhelm Roentgen discovered bonesgamma raysInfra redLightlongestmicrowavesPIRradio wavesradiotherapyshortestsoft tissuespeed camerasthermal imagingultra violetvacuumwavelengthX-rays[?]. These waves are absorbed by bonesgamma raysInfra redLightlongestmicrowavesPIRradio wavesradiotherapyshortestsoft tissuespeed camerasthermal imagingultra violetvacuumwavelengthX-rays[?], but pass easily through bonesgamma raysInfra redLightlongestmicrowavesPIRradio wavesradiotherapyshortestsoft tissuespeed camerasthermal imagingultra violetvacuumwavelengthX-rays[?], revealing the structure of the body.

Finally we come to the waves with the bonesgamma raysInfra redLightlongestmicrowavesPIRradio wavesradiotherapyshortestsoft tissuespeed camerasthermal imagingultra violetvacuumwavelengthX-rays[?] wavelength: bonesgamma raysInfra redLightlongestmicrowavesPIRradio wavesradiotherapyshortestsoft tissuespeed camerasthermal imagingultra violetvacuumwavelengthX-rays[?]. They can be used to kill cancer cells, we call this bonesgamma raysInfra redLightlongestmicrowavesPIRradio wavesradiotherapyshortestsoft tissuespeed camerasthermal imagingultra violetvacuumwavelengthX-rays[?].