waves are emitted by all objects but not visible to humans
the hotter the object, the more it emits
wave speed=frequency x wavelength
the higher the frequency, the shorter the wavelength.
the larger the amplitude, the greater the energy of the wave.
diffraction is when waves pass through a gap and spread out.
the longer the wavelength, the greater the diffraction.
electromagnetic waves transfer energy. examples are :gamma, x-ray, UV, visible light, infrared radiation, microwave and radio.
got these facts out of my physics book, hope they help :)
