the angle that the distance between to objects subtends at the observer's eye

a decrease in the observed wavelength

an opening in the shape of a circle through which diffraction takes place

sources whose phase difference is constant in time

the change in measured frequency when there is relative motion between source and observer

the distance between distant galaxies is increasing as space between them stretches

power of radiation per unit area; power per unit area by a wave - iintensity is proportional to the square of the amplitude of the wave

the change in the two-slit diffraction effect is taken into account

the condition for resolving two objecgts; resolution is possible when the central maximumin the diffraction pattern of one source coincides with the first minimum of the diffraction pattern of the other