Sun is in essence is a star closer to the earth. It emits many types of radiation. The visible light is a small proportion of all the radiation emitted by the Sun. The Sun emits cosmic rays, X-rays, Ultraviolet rays, visible light, infrared, microwave, radio waves, the wavelength increases from the cosmic to the radio waves. The heating comes from the infrared radiation. For example microwave ovens heat up food because the microwave is tuned to the waters vibrational energy and there fore it heats up the food as heat is absorbed by the food not the plate or container.
Radiation, although a wave of light, it should be considered as a form of energy and not as a continuous form but bundles of energy called photons. All waves have a property called wavelength and amplitude where it is twice the distance of the period of oscillation. Wavelength is a measure from one node to the same node. That is if V is the spped of a radiation and frequency is f, then V = f*w, where w is the wavelength. Energy = planks constant * w.
Radio waves
Radio waves vary in wavelength in the range of less than a centimeter to hundreds of metres. For example frequency modulated radio waves which in the radio dial 100 megahertz may have a wave length of 3 meters. A amplitude modulated radio wave in the radio dial of 750 kilohertz may have a wave length of 400 meters. Radio waves are used in irradiation of magnetic nuclei which can absorb energy and become opposed to external magnetic field and this can be recorded in a chart called magnetic resonance spectrum. These can be used by Chemists to study the structure of molecules and also can be used in medical field as a diagnostic tool as in Magnetic Resonance Imaging (MRI) scans which produces by using a computer to produce a coherent image to detect cancer cells.
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