Electromagnetic waves and black body radiation GapFill

Electromagnetic waves are transverse waves in electric and magnetic fields. Electromagnetic waves can have a variety of wavelengths and frequencies, forming a continuous spectrum.
The regions of the electromagnetic spectrum with some applications, from longest to shortest wavelength, are:

• radio waves - television and radio broadcasts
•  visible lightinfraredmicrowavesgamma rays - satellite communications, cooking food
•  microwavesinfraredvisible lightgamma rays - electrical heaters, cooking food, thermal cameras
• visible light -  medical imaging and treatmentsfibre-optic communicationsWi-Fiheating
•  ultravioletvisible lightinfraredgamma rays - hospital sterilisation, suntanning
• X-rays and gamma rays -  Wi-Fifibre-optic communicationsheatingmedical imaging and treatments

Radio waves are produced by  electrons moving between orbitalschanges in nucleichanging magnetic fieldsoscillations in electrical currents.
Gamma waves are produced by  electrons moving between orbitalschanging magnetic fieldsoscillations in electrical currentschanges in nuclei.

When light moves from one material into another, it can change direction due to the change in speed of the light; this is called  absorptiondiffractiontransmissionrefraction and is used in lenses.
Lenses can change the apparent size of an object; the change in size is known as magnification, which is given by the equation magnification =  object size - image sizeimage size - object sizeobject size ÷ image sizeimage size ÷ object size.
Lenses can either be either (the outer edge is thicker than the middle) or convex (the middle is thicker than the edge). Concave lenses produce images which  are always realare always virtualare always smaller than the objectare always the same size as the object, and convex lenses produce images which  can be either virtual or realare always virtualare always smaller than the objectare always the same size as the object.

Visible light can have many different colours, called the colour spectrum, which includes red, orange, yellow, green, blue, indigo and violet. Which colour an opaque object appears to be is related to  the brightness of the light absorbed by the object's surfacethe wavelengths of light that are transmitted through the objectthe wavelengths of light reflected by the objectthe intensity of light reflected from the object.
Visible light can be reflected, as seen in mirrors. When a surface is smooth, like a mirror, all the light is reflected in a single direction, known as  opacitydiffuseintegralspecular reflection. When a surface is rough, light is reflected in many different directions, known as  specularintegralopacitydiffuse reflection.
All objects emit radiation, with hotter objects emitting  higher intensity radiation at the same wavelengthhigher intensity radiation at shorter wavelengthsthe same intensity radiation at shorter wavelengthslower intensity radiation at shorter wavelengths. A perfect black body absorbs and re-emits all incident radiation.