If we let angle x be the location of the first minimum intensity point on either side of the center, W be the wavelength, and D be the width of the doorway, the equation Waves diffract differently depending on the object they are bending around. Gives x in terms of the wavelength and the width of the doorway. For a circular opening, the equation is slightly different. Angle x, W for wavelength, and D for width are all still the same. So, looking at these two equations you can tell that the extent of the diffraction depends on the ratio of the wavelength to the size and shape of the opening. If the ratio of W/D is large, then x is large. In this case, the waves are said to have a wide dispersion and the sound waves are spread out wider through the opening. Conversely, if the ratio of W/D is small, then x is small and the waves are said to have a narrow dispersion and the sound waves go through the opening without spreading out very much. Globe at Night ialah merupakan usaha untuk mengumpulkan data-data kecerahan langit malam dari serata dunia melalui penglibatan orang ramai tanpa memerlukan latar belakang saintifik yang tinggi.So, it makes sense that lower-frequency sounds typically have a wide dispersion and sounds with small wavelenths have a narrow dispersion. Portal astronomi paling aktif di asia tenggara Bureau international des poids et mesuresīiro berat dan ukur Antarabangsa.It is because the sound of the radio spreads around the corner of the wall due to diffraction of sound. The listener is able to hear the sound of the radio although it is behind the wall. To investigate the diffraction of sound waves the following experiment can be done:Ī listener is requested to stand on the other side of the corner of the wall so that the radio is beyond his vision. As we have already seen, long wavelength waves diffract more readily than those with short wavelengths. The reason is the sound waves have long wavelengths in air, ranging from a few centimetres up to several metres. This is why we can hear sound round a corner, or behind an obstacle. The light beam from the source is directed towards the slit.īy using a metre rule, measure the wide of the middle bright fringe = x Monochromatic light source, single slit plate, metre rule Responding variable: the wide of the middle bright fringeįixed variable: the monochromatic light (one wavelength only) To investigate the relationship the wide of the middle bright fringe increases and the size of slit decreases The wide of the middle bright fringe increases as the size of slit decreases The experiment to investigate the relationship between the size of slit and the wide of the middle bright fringe Waves diffracted after pass through a small slit. The wider middle bright fringe shows that the light The diagram shows the diffraction fringes. Thus a narrow object like a fine wire or a human hair can show the diffraction fringes at its edges similar to those produced by a small single slit. The diffraction of light waves occur when the light waves pass through a small slit or small pin hole.ĭiffraction occurs at all edges where waves can spread round into the shadow region. The experiment is repeated 5 times for with different widths of slit. The waves are freeze by a mechanical stroboscope.īy using a protractor, the angle of bent = θ The power supply is switched on to produce plane waves which propagate towards the aperture. The procedure of the experiment which include the method of controlling the manipulated variable and the method of measuring the responding variable.īy using a metre rule, the width of the slit is measured = a Ripple tank, lamp, motor ,wooden bar, power supply white paper, two pieces metal bar ,metre rule protractor and mechanical stroboscope. To investigate the relationship between the angle of bent and the size of aperture The angle of bent increases as the size of aperture decreases The experiment to investigate the relationship between the size of aperture and the angle of bent The following figure shows two examples pattern of the diffraction of the water waves. To investigate the diffraction of water waves an obstacle is placed at the centre of a ripple tank. The direction of propagation and the pattern of the wave change. When the diffraction of a wave happened, the wavelength, λ, the frequency, f and the speed, v do not change but the amplitude of the waves decrease. The smaller the aperture by comparison, the more wave bends. The amount the wave bends depends on the size of the aperture or barrier. The spreading or bending of waves as they pass through an aperture or round the edge of a barrier.
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