What is a Lens?

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Questions and Answers

What is the primary function of a lens?

To block light
To absorb light
To refract light (correct)
To reflect light

What is the main difference between a simple lens and a compound lens?

Compound lenses are used for telescopes only
Compound lenses use multiple lenses (correct)
Simple lenses are more expensive than compound lenses
Simple lenses are larger than compound lenses

What is the magnification power of the ocular lenses in a compound microscope?

50x
5x
10x (correct)
20x

What is an example of a device that uses a simple lens?

Magnifying glass (B) Signup and view all the answers

What is the purpose of corrective eyeglasses?

To see the world more clearly than the user's own eyes allow (D) Signup and view all the answers

How does a compound microscope differ from a simple lens in terms of magnification power?

A compound microscope has a greater capacity to magnify an object (C) Signup and view all the answers

What is the analogy used to explain the concept of compound lens magnification?

Moving 5 feet closer to an object six times (C) Signup and view all the answers

What is the purpose of the objective lenses in a microscope?

To increase the magnification of the sample (C) Signup and view all the answers

How do you calculate the total magnification of a microscope?

Multiply the ocular lens magnification by the objective lens magnification (C) Signup and view all the answers

What is the shape of a concave lens?

Thinnest in the middle and widest at the edges (A) Signup and view all the answers

What is the effect of a concave lens on light?

It spreads light into a wider arc (D) Signup and view all the answers

What is the purpose of a biconcave lens in corrective eyeglasses?

To correct nearsightedness (C) Signup and view all the answers

What is the shape of a convex lens?

Thickest in the middle and thinnest at the edges (A) Signup and view all the answers

What is the effect of a convex lens on light?

It focuses light on a central point (A) Signup and view all the answers

What is the purpose of a convex-concave lens in corrective eyeglasses?

To correct farsightedness (C) Signup and view all the answers

Study Notes

What is a Lens?

A lens is an instrument that refracts (or bends) light to allow users to see the world in a different way.
Lenses can enable people to see more clearly, magnify small objects, or see distant objects.

Types of Lenses

Simple Lens: uses a single lens to refract light, e.g., magnifying glass.
Compound Lens: uses multiple lenses, e.g., compound microscope.

Compound Microscopes

Use ocular lenses with 10x magnification and objective lenses with 4x, 10x, 40x, or 100x magnification.
Total magnification is calculated by multiplying the ocular lens magnification by the objective lens magnification.

Convex and Concave Lenses

Concave Lenses: thinnest in the middle, widest at the edges, spreading light into a wider arc.
Convex Lenses: thickest in the middle, thinnest at the edges, focusing light on a central point.

Corrective Lenses

Biconcave Lenses: correct nearsightedness by spreading light further back to focus on the retina.
Convex-Concave Lenses: correct farsightedness by reducing the focal point of light entering the eye to focus on the retina.