Lenses, images and ray diagrams

What is a lens?

A lens is a transparent optical device that refracts light to form images.

What are the two types of lenses?

The two main types of lenses are convex (converging) and concave (diverging).

How does a convex lens form an image?

A convex lens converges light rays to a focal point, forming a real or virtual image depending on the object’s distance.

How does a concave lens form an image?

A concave lens diverges light rays, which appear to come from a virtual focal point.

What is the focal length of a lens?

The focal length is the distance from the center of the lens to the focal point, where parallel light rays converge (convex lens) or appear to diverge (concave lens).

What is a real image?

A real image is an image that can be projected onto a screen, formed when light rays converge.

What is a virtual image?

A virtual image is an image that cannot be projected onto a screen, formed when light rays appear to diverge from a point.

How do you draw a ray diagram for a convex lens?

Draw parallel rays of light toward the lens, refract them to the focal point on the opposite side, and mark the image position.

How do you draw a ray diagram for a concave lens?

Draw parallel rays of light toward the lens, refract them away from the focal point on the same side of the lens, and mark the virtual image position.

What is the magnification formula for lenses?

The magnification is given by M=image height/object height

How does a lens magnify an object?

A lens magnifies an object by bending light rays in such a way that the image appears larger than the object.

How does the position of the object affect the type of image formed by a convex lens?

If the object is beyond the focal point, a real, inverted image is formed; if the object is closer, a virtual, upright image is formed.

What is the purpose of ray diagrams in optics?

Ray diagrams are used to visually represent how light rays pass through lenses or mirrors to form images.

How does the focal length affect the image produced by a lens?

A shorter focal length results in a more powerful lens that forms a larger image, while a longer focal length produces a smaller image.