Measuring the focal length of a lens for red and green light- Case Study

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Measuring the focal length of a lens for red and green light- Case Study

The case study that I will be studying is how the focal length of a lens for red and green light differs.

Eye defects is not something that is new it has been occurring for many years. Corrective lenses were said to be used by Abbas Ibn Firnas in the 9th century. Around 1284 in Italy, Salvino D'Armate is credited with inventing the first wearable eye glasses.

Focal length and optics both are related to the eyes. The eyes are used to see things without the eyes we would not know where we are going or what anything looks like.  

The diagram to the left shows a diagram of the eye.

 

The image above is of the human eye. The way the human eye works is that light enters the eye passing thro the iris, pupil and cornea. Once it reaches the lens of the eye the lens refracts the light further and it is made to converge at a single point at the back of the eye where the retina is. Once this happens the optical nerve sends messages to the brain and it is the brain that actually converts this to an image for us to see.

The lens of an eye works in a similar way to a converging lens. A converging lens refracts light that passes through it to a single point; this is known as the focal point. The diagram below shows some information on the focal point and focal length:

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Eye defects:

The eye above shows an eye that has no problems with it. However you can have eyes that have certain defects. There are two main problems with eyes.

Firstly myopia (more commonly known as short sight) this is when a human can see objects that are closer to them better than objects which are further away. Myopia is caused when the cornea is too curved, or your eyeball too long this means that when light passes through the lens it converges to a point that is ahead of the ...

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