1 Flashcards
Fermat’s principle
The path taken between two points by a ray of light is the path that can be traversed in at least time
(Can be used to describe the properties of reflection and refraction)
Magnification Equation
m=yi/y0
yi=height of image
y0 = height of object
m = magnification
Lensmakers equation
1/f=(n-1)(1/r1+1/r2)
f=focal length
n= refractive index
r1 = curvature radius of the first surface
r2 = curvature radius of the second surface
Lens equation
n1/p + n2/i = n2-n1/r
p= object distance
i = image distance
r = focal length
Iris
Coloured part of the eye that controls how much light is allowed in
Pupil
Hole at the centre of the eye through which light enters
Cornea
Outer part of the eye’s focusing system
Lens
Clear part of the eye behind the iris that helps to focus light, or an image, on the retina
Vitreous Gel
A clear gel that fills the inside of the eye
Retina
light sensitive tissue lining at the back of the eye. Converts light into electrical impulses that are sent to the brain through the optic nerve
Macula
Small sensitive area of the retina that gives central vision. Located at the centre of the retina and contains the fovia. Responsible for reading vision
Fovia
Centre of the Macula, gives the sharpest vision
Optic nerve
A bundle of over one million nerve fibres that carry electrical impulses from the retina to the brain
Accomodation
The ability for the lens to change its shape to focus from distant to near objects and vice versa. The ciliary muscles change the shape of the lens. Lens flattens for distant objects and rounds for nearer objects
Index of refraction of cornea
nc=1.376
Similar to the refractive index of water, hence why it is difficult to see underwater
