What are electromagnetic waves that you can see?

Radio waves: If our eyes could see radio waves, we could (in theory) watch TV programs just by staring at the sky! Well not really, but it's a nice idea. Typical size: 30cm-500m. Radio waves cover a huge band of frequencies, and their wavelengths vary from tens of centimeters for high-frequency waves to hundreds of meters (the length of an athletics track) for lower-frequency ones. That's simply because any electromagnetic wave longer than a microwave is called a radio wave. Microwaves: Obviously used for cooking in microwave ovens, but also for transmitting information in radar equipment. Microwaves are like short-wavelength radio waves. Typical size: 15cm (the length of a pencil). Infrared: Just beyond the reddest light we can see, with a slightly shorter frequency, there's a kind of invisible "hot light" called infrared. Although we can't see it, we can feel it warming our skin when it hits our face-it's what we think of as radiated heat. If, like rattlesnakes, we could see infrared radiation, it would be a bit like having night-vision lenses built into our heads. Typical size: 0.01mm (the length of a cell). Visible light: The light we can actually see is just a tiny slice in the middle of the spectrum. Ultraviolet: This is a kind of blue-ish light just beyond the highest-frequency violet light our eyes can detect. The Sun transmits powerful ultraviolet radiation that we can't see: that's why you can get sunburned even when you're swimming in the sea or on cloudy days-and why sunscreen is so important. Typical size: 500 nanometers (the width of a typical bacteria). X rays: A very useful type of high-energy wave widely used in medicine and security. Find out more in our main article on X rays. Typical size: 0.1 nanometers (the width of an atom). Gamma rays: These are the most energetic and dangerous form of electromagnetic waves. Gamma rays are a type of harmful radiation. Typical size: 0.000001 nanometers (the width of an atomic nucleus).