Методичне забезпечення

Radial - the direction towards or away from the centre of a spherical body

Radiation - energy in the form of electromagnetic waves

Radioactivity - the phenomenon in which nuclei emit

Random uncertainty - an error due to inexperience of the observer and the difficulty of reading instruments

Rarefaction - a point in a medium through which a wave is travelling that has minimum density

Ray - the direction of energy transfer of a wave

Rayleigh criterion - the condition for resolving  two objects; resolution is possible when the central maximum in the diffraction pattern of one source coincides with the first minimum of the diffraction pattern of the other real gas a gas obeying the gas laws approximately for limited ranges of pressures, volumes and temperatures

Red-shift - an increase in the observed wavelength

Reflection - the scattering of radiation off a surface such that the angle of incidence is equal to the angle of reflection

Refraction - the change in speed of a wave as it enters another medium and the subsequent change of direction (except at normal incidence)