Non-ionising radiation is found at the long wavelength end of the spectrum and may have enough energy to excite molecules and atoms causing then to vibrate faster. This is very obvious in a microwave oven where the radiation causes water molecules to vibrate faster creating heat.
Non ionising radiation ranges from extremely low frequency radiation, shown on the far left through the radiofrequency, microwave, and visible portions of the spectrum into the ultraviolet range.
Extremely low-frequency radiation has very long wavelengths (from three kilometres to thousands of kilometres) and frequencies in the range of 100,000 hertz or less. Radiofrequencies have wavelengths from a fraction of a centimetre up to 3000 meters and frequencies in the range of 100,000 hertz to 300 billion hertz. Microwaves that we use to heat food have wavelengths that are about 12.5 centimetres long and have frequencies of about 2.4 billion hertz.