The frequency range is from × Hz to × Hz. It obeys the laws of reflection and refraction. It undergoes interference, diffraction and can be polarised. It exhibits photo-electric effect also.
It can be used to study the structure of molecules, arrangement of electrons in external shells of atoms. It causes sensation of vision. Ultraviolet radiation It is produced by Sun, arc and ionized gases. Its frequency range is from × Hz to Hz.
Measuring the speed of light using the microwave oven Nowadays the microwave oven is very commonly used to heat the food items. Micro waves of wavelengths mm to cm are produced in these ovens. Such waves form the standing waves between the interior walls of the oven. It is interesting to note that the speed of light can be measured using micro wave oven.
(a) (b) Hot Hot Hot Hot Hot H H H H H o H o o (c) (d) We studied about the standing waves in XI physics, Volume , Unit . The standing waves have nodes and antinodes at fixed points. At node point, the amplitude of the wave is zero and at antinodes point, the amplitude is maximum. In other words, the maximal energy of microwaves is located at antinode points.
When we keep some food items like chappathi or choclate (after removing the rotating platform) inside the oven, we can notice that at antinode locations, chappathi will be burnt more than other locations. It is shown in the Figure (c) and (d). The distance between two successive burnt spots will give the half wavelength of microwave. The frequency of microwave is printed in the panel of oven.
By knowing wavelength and frequency of microwaves, using the formula vλ = c, we can calculate the speed of light c . Activity 12th - 12th - - - - - Unit Electromagnetic waves B = T