HUMAN EYE

 Human Eye: working of human eye, Persistence of vision, Power of accommodation of human eye, Defects of vision.

The Human Eye: It is a natural optical instrument which is used to see the objects by human beings. It is like a camera which has a lens and screen system.

Have you ever thought why people wear spectacles why not anything else whey they are not able to see clearly.

The simple answer is people who are not able to see objects near to them after 25 cm they are suffering from myopia.

Myopia - It is a defect .It needs a convex lens of prescribed power by the doctor.

The simple answer behind this defect is, this happens due to the increase in focal length or elongation of eye ball due to which image is formed before retina.

Retina is a part of eye where the image is formed.It has light sensitive cell which gets activated and generate the electrical signal.

Hypermetropia -----------

It is a defect which is caused by the shortening of eye ball.This defect make the person unable to the objects before 25cm.And they have difficulty to see nearby objects so they use a concave lens to fix their vision which makes the image on retina.

Have u ever thought why the sky is only blue in colour it could have some other colour like yellow or green but only blue why ? 

The simple answer behind this is scattering of light.To understand this we must have a knowledge about wavelength.

There are 7 wavelengths 

*From top*

RED,ORANGE,YELLOW,GREEN,BLUE,INDIG-O,VIOLET.

RED - It has the Highest wavelength

ORANGE - It has the less wavelength than red.

YELLOW- It has less wavelength than orange.

GREEN- It has less wavelength than yellow.

BLUE- It has less wavelength than green.

INDIGO- It has less wavelength than blue.

VIOLET- It has the lowest wavelength

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