Science 8Unit C: Light and Optical Systems

Science InAction 8

Our knowledge about light and vision comes from explanations, inventions, and investigations

Section 1.2: Pages 182-187

Optical Devices 1.2Learner Outcome

I can investigate the development of microscopes, telescopes and other optical devices; and describe how these developments contributed to the study of light and other areas of science

Microscopes Optical Device = any

technology that uses light

Father and son team of Hans and Zacharias Jansen of the Netherlands built the first microscope in about 1595

Microscopes In 1673, Antonie van

Leeuwenhoek, a Dutch storeowner turned microbiologist, perfected a simple microscope with a very short focus that was preferable to the compound microscopes that were available at that time.

Microscopes Microscopes allow to

see in great detail by combining the power of two lenses: objective lens and eyepiece lens

All microscopes have this same basic principle.

Lens diagram of a microscope

Telescopes Developed in the Netherlands

in the 17th Century

Galileo, an Italian scientist, later made better and better telescopes.

It allowed him to make astronomical predictions and discover new objects in the night sky

Telescopes Two characteristics

Telescopes magnify light – eg. could see Venus

Telescopes collect light – eg. could see faint objects, like Jupiter

Two types of telescopes

Reflecting Telescope

Large circular mirror that curves inward

Smaller mirror inside that reflects light to eyepiece

Two types of telescopes

Refracting Telescope

Two lenses – one on either end of a long tube

Larger lens gathers light and focuses it toward the eyepiece.

Binoculars Two short refracting

telescopes that are fixed together.

Not as powerful due to their small size.

More convenient to carry.

The Big Idea

Light tends to travel straight, but will bounce and bend predictably when it strikes various substances.

Did you …… investigate the development of

microscopes, telescopes and other optical devices; and describe how these developments contributed to the study of light and other areas of science?

Check and Reflect Questions1-4, page 186

1. What optical device would you use to view the peak of a nearby mountain and why? Is there another device you could use?

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2. How is a microscope similar to a refracting telescope? How is it different?

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Check and Reflect Questions1-4, page 186

3. Compare and contrast refracting and reflecting telescopes.

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4. How does a microscope work?_________________________________________________

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Assess Your Learning page 187

1. What did Euclid discover about light?

3. Describe three properties of light.

5. Could a mirror be called an optical device? Explain why or why not.

7. Why was the invention of the telescope so important?

9. How did Newton change scientific ideas about how colored light is formed?