The aperture or the diffracting object effectively then becomes the second source of the wave. (b) The diagram shows the bright central maximum, and the dimmer and thinner maxima on either side. The central maximum is six times higher than shown. (a) Monochromatic light passing through a single slit has a central maximum and many smaller and dimmer maxima on either side. The wave then bends around the corners of an obstacle, through apertures into the regions of the shadow of the obstacle. Figure 4.2.2: Single-slit diffraction pattern. Note: Diffraction refers to the phenomenon of a wave encountering an opening or obstacle. Therefore to encounter diffraction on electromagnetic waves in our normal lives, we would require microwaves and not visible light since microwaves have a much higher wavelength and the longer wavelengths of about $3\ cm$ can be seen in low light conditions.
This does not happen in electromagnetic waves.įor observing the phenomenon of diffraction, the order of the magnitude of the wavelength of the waves should be comparable to that of the slit width. The motion of vibration in longitudinal waves is in the same direction as the wave propagation. Sound travels by longitudinal waves which radiate outward in concentric circles. The general wavelength of visible light ranges from $7000 \times m$. (Because sound waves are much larger than light waves, however. Any type of energy that travels in a wave is capable of diffraction, and the diffraction of sound and light waves produces a number of effects. The wavelength of sound generally ranges from $17\ m$ to $15\ mm$. Diffraction is the bending of waves around obstacles, or the spreading of waves by passing them through an aperture, or opening. The frequency of human audible sound waves lies from $20\ Hz$ to $20\ kHz$. The wavelength of sound waves is much higher than that of visible light. This condition is satisfied only for sound waves in everyday life. and so objects such as the edges of walls will cause diffraction and enable sound to travel round corners. If you live near the sea, have a look at waves on a windy day hitting a harbour wall. All waves tend to spread out at the edge when they pass through a gap or past an object. A really good example of diffraction can be seen with another type of wave barrier a harbour or dock wall. Its certainly possible to hear a sound made from around a corner. Ocean waves diffract around barriers like reefs, peninsulas, and docks. Like other wave phenomena, this is not unique to light.
Figure 3.1.3 Diffraction from Huygenss Principle. Have a look at this a simulation of three. Diffraction can be clearly demonstrated using water waves in a ripple tank. The amount of diffraction (spreading or bending of the wave) depends on the wavelength and the size of the object. Diffraction is the bending of waves around small objects and the spreading out of a wave through small openings. The result is that the wave 'bends around corners,' a phenomenon known as diffraction. Waves can spread in a rather unusual way when they reach the edge of an object this is called diffraction. For diffraction to occur, the slit width should be comparable to the wavelength of the light or sound waves. Figure 1 - Example of an incoming sound wave, reflecting back off a large surface. Hint: The reason for the diffraction of sound waves being more evident in daily experience than light waves is that sound waves have much higher wavelength compared to the visible light waves.