Light and Lenses

Refraction and Lenses

• What determines the type of Image Formed by a Lens?

Lenses

• A lens is a curved piece of glass (or other transparent material) that refracts light

Types of lenses

​The are two types of lens

Convex Lens- is a converging lens since it can bend light rays inwards and converge at the focal length. Convex lenses are mainly used to correct hypermetropia or long-sightedness. They are used in cameras to focus light and produce a clear and crisp image.

​Concave Lens- known as a diverging lens because it is shaped round inwards at the centre and bulges outwards through the edges, making the light diverge. They are used to treat myopia or Short sightedness as they make faraway objects look smaller than they are.

• caves in" on either side of lens"

• thinner in the middle than at the edges

• The parallel light rays enter and then exit angled away from one another never meeting at a focal point

• Like a Convex Mirror it produces only virtual images

Concave Lens

• Thicker in the center than the edges

• As parallel light rays enter the lens they exit at an angle so they meet at a focal point

• If the object is between the focal point and the lens then a virtual image is produced

• If the object is beyond the focal point then a real image is produced.

​

​Convex Lens

Multiple Choice

Which type of lens in thinner in the middle and thicker on the edges

• Concave Lens

• Convex Lens

Multiple Choice

What type of lens do we have in our eye?

• Convex

• Concave

• Retina: thin layer of cells that line the back of the eye

• Lens: convex shape, bends light to form an image on the retina

• pupil: the muscle that contracts when exposed to sunlight

• Iris: the color part of the eye

• Cornea: the protective outer layer

​Parts of the Human Eye

Multiple Choice

What do we call the muscle in the eye that contracts in sunlight?

• retina

• lens

• pupil

Multiple Choice

What do we call the back of the eye where images are projected as light?

• pupil

• retina

• iris

• cornea

Multiple Choice

What is the protective layer on the outer eye called?

• Cornea

• lens

• pupil

Multiple Choice

What is the part of the eye that bends light so that an image can be projected onto the retina?

• optic nerve

• lens

• pupil

• I don't know

Multiple Choice

What do we call the muscle in the eye that contracts in sunlight?

• I have no idea b/c I wasn't mentally present in class.

• retina

• lens

• Pupil

Multiple Choice

What do you call the colored part of the eye?

• Tina

• Iris

• Ike

• Optical nerve

Multiple Choice

What is the protective layer on the outer eye called?

• The corona

• The cornea

• The Coroner

• The Corner