Why there is a bend in thermometer?

Answer 1

The simple answer: light refract under water thus the image of the ruler is slightly warped due to this effect.

The reason light refracts under water is the velocity of light (or any electromagnetic wave in fact) is slower when traveling through a denser medium (it reaches its fastest speed when in a vacuum). Since the light hits the different medium at an angle (or else it wouldn't refract), one side of the wave slows down, thus it bends towards the slower side, for instance imagine you are roller skating on the road, but you put one foot on the lawn, you immediately start turning towards the lawn since the grass slows one side of your body down, its pretty much the same thing with light, it bends toward the slower side.

Refraction is modeled by Snell's Law:

n1sin(theta1) = n2sin(theta2)

where n is the index of refraction

theta is the angle of incidence(the angle measured from the 90 degree mark of the surface)
a pencil in water looks bent because of refraction. when light enters a substance with a different density than the one it came out of, the light either slows down or speeds up. this makes the light appear bent. If there is a pencil in the water, it appears bent because the light is traveling at different speeds through water and air.

Answer 2

A straw looks "bent" when it's in water because water causes light to "change course" when it moves from air into the water. The light will again be caused to change course when it leaves the water to go back into air. This is called refraction. Refraction is a fundamental property exhibited by a wave that changes mediums through which it is traveling.

or...

making it simple..

A straw seems bent because water is denser than air, so when it changes from air to water is applied it seems bent.

Answer 3

Just as a funhouse mirror distorts the shape of objects, viewing an object through water can alter its apparent shape. Light waves travel more slowly through water than through air. One of the properties that a light wave shares with all other waves (for example, sound waves) is that when it passes into a medium that propagates it at a different speed, it changes direction slightly. This change in direction is called "refraction," and it makes objects look like they are in a different location than they actually are, similarly to the way that reflection of light off of a mirror makes it look like objects are behind the mirror when they really are in front of it.

Answer 4

It's because of refraction-when light wave passes from one medium to another, causing the waves velocity to be altered so the light bends.

Answer 5

Refraction. Although it appears broken or bent, it's actually not. Refraction is really the key word here.

Answer 6

TTo stop Mercury falling back before taking a reading

Answer 7

Because of the refraction of light.

Answer 8

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