Lenses Getting the Idea S4P1.c

Lenses A lens is a clear material with one or two curved surfaces. It is used to change the direction of light. Things can look bigger or smaller if you look at them through a lens.

Refraction Light can change speed when it moves from one material to another. The change in speed causes light to change direction. If the surface of a material is curved, the light can change direction even more. Refraction is a change in the direction of light. A lens increases the refraction of light.

Different Kinds of Lenses Convex A convex lens is a lens that is thicker in the middle than at the edges. Light that moves through a convex lens is bent inward. The rays of light meet at a point called the focus.

Different Kinds of Lenses Concave A concave lens is a lens that is thicker at the edges than in the middle. Light is bent outward when it moves through a concave lens.

Uses of Lenses The size of an object can seem different if you look at it through a lens. Convex lenses are often used to make objects look bigger or seem closer. Objects seem smaller of farther away through a concave lens. The next slide lists some objects that contain lenses. Some of these things have both a convex lens and a concave lens. Eyeglasses used to see near things clearer have a convex lens. Eyeglasses used to see far things clearer have a concave lens.

Objects that contain one or more lenses Eyeglasses Camera Binoculars Telescope Microscope Magnifying glass

Prisms A prism is three-dimensional, triangular object made of clear glass or plastic that can change the path of light. Prisms are used in some binoculars and cameras. Prisms can also be used to split white light into colors of light. White light is a mix of all colors of light. A prism splits the white light by changing the path of light at different amounts for different colors.

Prisms

Discussion Question Makayla notices that a book she is reading looks different when she holds it behind a glass of water. The words seem to have a different size. A glass of water is MOST like what type of lens? Why?

Lesson Review George needs eyeglasses to make things that are close to him look clear. What type of lens should be in his glasses? a. Concave b. Convex c. Reflective d. Translucent

Lesson Review A prism is MOST useful in which of the following? a. Binoculars b. Eyeglasses c. Magnifying glass d. Mirror

Lesson Review A raindrop splits sunlight into different colors of light. This also happens in a a. Camera b. Convex lens c. Microscope d. Prism

Lesson Review A concave lens MOSTLY changes a light’s a.Color and direction b.Direction and speed c.Strength and color d.Speed and strength

Lesson Review Think about what happens to light when it moves through each of the following things. Which is MOST like a convex lens? a.A sheet of waxed paper b.A clear glass window c.A clear jar filled with water d.A piece of clear plastic wrap