is clearly nothing to distinguish between (i) and (ii). Here only the relative motion between the source and the observer counts and the relativistic Doppler formula is the same for (i) and (ii). For light propagation in a medium, once again like for sound waves, the two situations are not identical and we should expect the Doppler formulas for this case to be different for the two situations (i) and (ii). .
. × – m. . (a) The size reduces by half according to the relation: size ~ # /d.
Intensity increases four fold. (b) The intensity of interference fringes in a double-slit arrangement is modulated by the diffraction pattern of each slit. (c) Waves diffracted from the edge of the circular obstacle interfere constructively at the centre of the shadow producing a bright spot. (d) For diffraction or bending of waves by obstacles/apertures by a large angle, the size of the latter should be comparable to wavelength.
If the size of the obstacle/aperture is much too large compared to wavelength, diffraction is by a small angle. Here the size is of the order of a few metres. The wavelength of light is about × – m, while sound waves of, say, kHz frequency have wavelength of about . m.
Thus, sound waves can bend around the partition while light waves cannot. (e) Justification based on what is explained in (d). Typical sizes of apertures involved in ordinary optical instruments are much larger than the wavelength of light. .
nm. . (a) Interference of the direct signal received by the antenna with the (weak) signal reflected by the passing aircraft. (b) Superposition principle follows from the linear character of the (differential) equation governing wave motion.
If y and y are solutions of the wave equation, so is any linear combination of y and y . When the amplitudes are large (e.g., high intensity laser beams) and non-linear effects are important, the situation is far more complicated and need not concern us here. . Divide the