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20 solved problems in waves and acoustics
- 1. 20 Solved Problems in Waves and Acoustics Source: www.physicslectures.info By mjaafar
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- can a surface be considered polished for some waves and not for others? cite an example. light waves are reflected either diffusely or “specularly” by a surface depending on the wavelength of the wave and the degree of roughness of a surface, if the surface roughness is greater than the wavelength of the wave, the surface will be rough for the wave but if the surface roughness is less than the wavelength of wave the surface will be polished for the wave. a surface can be rough for some em waves and rough for others because waves have different wavelength , if the surface is rough the waves will be reflected as diffuse reflection and if the surface is smooth the wave will be reflected as specula reflection. is a mirage the result of reflection or refraction? why does it happen? mirage is as a result of light refraction , it occur due to change of medium of sunlight. in a sunny day, the sun heat the road, the volume of air just above the road surface is hotter than the threst of the surrounding air, hot air tends to be less dense than cooler air, difference variation of densities causes ray of light travelling between this medium to refract and this appear as a mirage. in which medium does light travel faster in thin air or dense air light travel faster in air than in a dense air, cooler air tend to be denser than hotter air, therefore light will travel faster in hotter air than in cooler air or in other word light will travel faster in thin air than dense air because they different index of refraction. does the refraction of light make a swimming pool seem deeper or shallower refraction of light will make a swimming pool shallower. how does the speed of light that emerges from a pane of glass compare with the speed of light incident on the glass? the speed of light that originates from the pane of glass and that of the incident light is the same because they are both in the same medium ( air) , the speed only changes when the light enters another medium. what is the fate of the energy in infrared light incident on glass? the energy in the infrared radiations incident on the glass increases the temperature of the glass, if it is continues it will upset the glass and melt it to liquid. the infrared is a spectrum of em waves not seen by eye but can be detected by skin( heat). the whiteness of clouds, unlike the blueness of the sky, primarily involves? the whiteness of cloud is, unlike the blueness of the sky that only involve the scattering of blue light, is as a result of complete scattering of all wavelength of visible light. for the cloud to appear whites all colors of light must be scattered and when this happen they appear as white light. what is the effect on the color of a cloud when it contains an abundance of large droplets? answer this question why are infrared waves often called heat waves? because they are detected as heat by human skin. what is the fate of the energy in visible light that is incident upon clear glass the energy will be transmitted, increasing the kinetic energy and then the temperature of the glass. what is the fate of the energy in ultraviolet light incident on glass answer this question what is the color of the peak frequency of solar radiation when it is plotted versus wavelength? yellow green what color light is transmitted through a piece of red glass? red , all other colors are reflected when something is painted red, what color is most absorbed? any other color apart from red why are red, green, and blue called the additive primary colors?, because they are combined in the right proportion they form white colors, and canbe combined to form any other coor in the spectrum of rambow. what is the color of visible light of the lowest frequencies? of the highest frequencies? red has the lowest frequency while violet has the highest frwequency , frequency is an inversely of frequency, from ROYBIV, starting from red with 400nm to violet with 700nm, surely how does the frequency of a radio wave compare to the frequency of the vibrating electrons that produce it? they are the same what is the wavelength of a wave that has a frequency of 1 hz and travels at 300,000 km/s? c = fλ f =c/λ f =300,000 km/1 =300, 000km/s in what region of the electromagnetic spectrum is the resonant frequency of electrons in glass? in the ultraviolet region of em spectrum why does the sun look reddish at sunrise and sunset but not at noon because the longest wavelength of the white light are being scattered , during the sunset and sunrise when the sun is farther away from the earth and only the longest wavelength