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Which of the following phenomena best explains why a straw appears bent when partially submerged in a glass of water?
Total internal reflection
Refraction of light
Diffraction of light
Dispersion of light
Refraction of light
The bending of a straw in a glass of water is caused by the refraction of light, which occurs when light rays change direction as they pass from one medium (air) to another (water) ┬╖ Because the speed of light is different in water compared to air, the light rays bending towards the normal make the submerged portion of the straw appear at a displaced position to an observer.
The bending of a straw in a glass of water is caused by the refraction of light, which occurs when light rays change direction as they pass from one medium (air) to another (water) ┬╖ Because the speed of light is different in water compared to air, the light rays bending towards the normal make the submerged portion of the straw appear at a displaced position to an observer.
Think of a car driving on a smooth road hitting a patch of mud at an angle; the tires that hit the mud first slow down, causing the car to turn or change its path just like light.
RAS: Rare to A denser, light bends towards the Normal (RAS - Refraction Air-to-Something).
n=vcтАЛ тАФ Refractive index n is the ratio of speed of light in vacuum c to speed in medium v
n1тАЛsin╬╕1тАЛ=n2тАЛsin╬╕2тАЛ тАФ Snell's Law relating refractive indices and angles
Light travels at different speeds in different media ┬╖ According to Snell's Law, when light enters an optically denser medium like water from a rarer medium like air, it bends towards the normal ┬╖ The eye perceives the light rays as if they were traveling in a straight line, creating a 'virtual' image of the object at a shallower depth, which causes the perceived bending effect.
Refraction occurs only at the interface of two transparent media with different refractive indices.
The apparent depth of an object is always less than its real depth when viewed from a rarer medium.
Light changes its velocity and wavelength, but its frequency remains constant during refraction.
Formation of images by lenses
Twinkling of stars in the night sky
Refractive index of water is approximately $1.33$.
Option A (Total internal reflection) requires light to travel from a denser to a rarer medium at an angle greater than the critical angle, which is not the primary cause here.
Option C (Diffraction) refers to the bending of light around corners of obstacles, which is not involved here.
Option D (Dispersion) refers to the splitting of white light into its constituent colors, like in a prism.
B is correct тАФ Refraction is the physical phenomenon responsible for the apparent displacement of objects submerged in a different medium.
Always remember that refraction is responsible for both the 'bent straw' illusion and the 'apparent depth' of swimming pools; both arise from the same change in light speed at an interface.