MIRAGE is formed by the phenomenon of total INTERNAL reflection of light. Mirage is formed in extremely high or low temperature conditions.
For example: When a sand surface (desert) or road surface is heated, the air above this surface is also heated and rises up.
As a consequence, the density of air in the lower level is less than that of upper level.
Now , the light from any object starting from the upper layers (denser medium) travels to lower layers ( rarer medium), total internal reflection takes place i.e, the light is reflected back towards the denser medium. When these light rays reflected back, it seems that the light rays are refected from some bright reflecting surfaces on the ground. Hence the image is seen below the object.
Loudness of a sound is the characteristic of a sound which depend on the intensity of energy it carries. Intensity of a sound is the amount of energy passing through a surface area of one square metre held perpendicular per sec. Intensity depends on square of amplitude of the wave passing. Hence we can say Loudness is directly proportional to the square of Amplitude. If amplitude is doubled, loudness becomes four times. Loudness depends on distance of source from the listener. Loudness depends on resonance also.
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