# Blog

## What kind of wavelength do television signal's have? ## Which has longer wavelength visible light or radio waves?

• A radio wave has a much longer wavelength than visible light. Humans use radio waves extensively for communications. The wavelengths of radio waves range from a few millimeters (tenths of inches) to hundreds of kilometers (hundreds of miles).

## What wave has the longest wavelength?

• See explanation. Color implies visible light, so to answer your question: red light has the longest wavelength (≈620-740 nm). However, there also exists light with even longer wavelengths that are not visible to the human eye, from infrared light to radio waves (with wavelengths that are meters long!)

## How to calculate wavelength?

• Use a photometer to measure the energy of a wave.
• Convert the energy into joules (J).
• Divide the energy by Planck’s constant,6.626 x 10 -34,to get the frequency of the wave.
• Divide the speed of light,~300,000,000 m/s,by the frequency to get wavelength.  