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Chapter 3

3.0

Human Eye

P. 252-255 BC Science Connections

Vocabulary & Concepts

retina cornea pupil lens

iris optic nerve ciliary muscles aqueous humour

sclera vitreous humour

Parts of the Eye

Here’s a video describing the human eye: https://www.youtube.com/watch?v=cFVbLnXWn6A

It’s called, Bill Nye the Science Guy on the Eyeball on Youtube, or you can access it on your teacher’s Weebly.

What is interesting about the image of “kid on a stick” as it travels to the back of your eye?

___________________________________________________________________________________________

What organ helps us make sense of what we see? ___________________________________________________

Mini Activity

1. Find a handheld mirror and take a good look at yourself! 2. Locate your iris. What colour is your iris? ________________________ 3. Go to someplace that is dim, but still bright enough for you to see your reflection. 4. Find a flashlight. Carefully bring the flashlight close to your face while obseving your eyes in the

mirror. Be careful not to shine the light directly into your eyes!

Drawing of your eye in dim light Drawing of your eye in bright light

5. What happens to your eye in low light vs. bright light? Explain WHY this happens using the words

pupil, iris, and light.

6. When you can’t see in the dark, you are often told to “wait for your eyes to adjust”. What does this

mean? ___________________________________________________________________________________

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Here’s a video describing the human eye: https://www.youtube.com/watch?v=syaQgmxb5i0 It’s called, How Your Eyes Work on Youtube, or you can access it on your teacher’s Weebly. Additional research might be needed to fill out the diagram below.

Part of the Eye (word bank for above diagram)

What is its function?

Cornea

Pupil

Lens

Iris

Ciliary muscles

Vitreous humour

Aqueous humour

Retina

Optic nerve

Sclera

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Critical Thinking

1. What would happen to your vision if your ciliary muscles are too weak? Why?

2. What would happen to your vision if you got hit in the eye and severed your optic nerve?

Comparing the Pinhole Camera to the Human Eye

Brainstorm

What similarities and differences do you notice between the eye and the camera from the pictures above?

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Label the parts of the eye below, then research the functions of the parts of a basic camera. Can you match the

parts of the eye with their corresponding parts in a camera? Use the provided table to organize your answers.

Part of a Camera The Function of the Camera Part Is similar to the ______

in the eye

Lens

Focus knob

Aperture ring

Aperture

Cameral shell

Film

Watch Eye vs. Camera Michael Mauser on Youtube at

https://www.youtube.com/watch?v=OGqAM2Mykng or from your teacher’s Weebly.

camera shell

aperture

film

aperture ring

lens

focus knob

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Mini Activity

One major difference between a camera and your eye is that your eye has a blind spot.

1. Hold these notes with your right hand in front of your face, arm fully extended. Make sure the

notes are centered in your field of vision.

2. Look at the image below with the X and O.

3. Cover your left eye with your left hand.

4. Look at the X.

5. Slowly move these notes closer and closer to your face, while still looking at the X.

6. What eventually happens? __________________________________________________________.

You have just discovered your blind spot!

7. Using your answer to #6, why is it important to have two eyes?

8. What part of the eye is responsible for capturing light, similar to how photo paper in the pinhole

camera captures light? ___________________

9. There is one spot inside the eye where the structure from #8 does not exist. Where do you suppose

that is? Circle that spot on the diagram below which shows light entering the eye.

10. Why do you think a blind spot exist in our eyes and that there’s no way we can get rid of it?

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Chapter 3

3.1 - 3.2

Properties of Electromagnetic Radiation

P. 186-219 BC Science Connections

Vocabulary & Concepts

light ray wave wavelength amplitude

frequency crest trough visible light spectrum

photon wave-particle duality

Basic Properties of Light

Mini Activity

1. Find a source of light where you are. 2. Using that source of light, make a shadow with your hand. 3. Do a quick sketch of the light source, your hand, and your shadow in the box below.

a) Draw an arrow from the light source to your hand to represent travelling light. b) Label the arrow as “light ray”

4. What happens to light as it reaches your hand? Support your explanation with your observations.

5. Does light travel in straight paths or does it bend? __________________________________________

If light were to travel in straight paths, then when light hits an obstacle, we should see

If light were to travel in curves, or if it can bend, then when light hits an obstacle, we should see

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Mini Activity

1. Find a flashlight and shine it on a wall 5 cm away. This is best done in a dark room. 2. Slowly move away from the wall. 3. Do a quick sketch of how the light appears on the wall.

Flashlight at 5 cm Flashlight at 30 cm Flashlight at 1 m

How bright is the light on the wall?

How bright is the light on the wall?

How bright is the light on the wall?

4. Below are some ray diagrams that show the direction of travelling light from a flashlight. Which

diagram is consistent with what you have observed in this activity?

A.

B.

C.

D.

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Light Behaves as a Wave

So what exactly is light? Well, light is a form of energy that is visible to us. There are many forms of invisible

energy in the world, such as:

a) Microwaves heat your food, but you cannot see the microwaves being absorbed by your food.

b) Somehow your phone receives wifi, but you cannot see this wifi travelling through the air.

c) UV rays and X rays can damage your body, but you cannot see them doing the damage.

d) Infra red waves travel from your wii remote to your wii, but you cannot see anything between your

remote and the wii.

Altogether, the collection of these energies is called the electromagnetic spectrum.

Watch Tour of the EMS - Introduction on Youtube at https://www.youtube.com/watch?v=lwfJPc-rSXw or on your teacher’s Weebly. Then answer the following questions.

Try this interactive learning tool by NOVA to read more about the special types of electromagnetic waves! You can find it on your teacher’s Weebly or at this address: http://www.pbslearningmedia.org/resource/phy03.sci.phys.mfw.spectrum/tour-the-electromagnetic-spectrum/

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Electromagnetic rays are natural. They are generated by chemical reactions and nuclear reactions in stars. Our

sun generates quite a bit of them! Scientists can artificially generate them too.

Try this interactive learning tool by BBC to learn about how we use electromagnetic waves I our daily life. You can find it on your teacher’s Weebly or at this address: http://www.bbc.co.uk/schools/gcsebitesize/science/21c_pre_2011/radiation/electromagnet Icradiationact.shtm

Electromagnetic Wave What are they used for?

Radiowaves

Microwaves

Infrared

Visible light

Ultraviolet

X-rays

Gamma rays

So, light is just another form of energy on the electromagnetic spectrum. It’s special because it just so happens

to be visible to us. We say light, and other forms of energy, travels in waves.

Research Use Google to help you label and define the following words on the wave below:

a) Crest: ______________________________________________________________________________

b) Trough: ____________________________________________________________________________

c) Amplitude: _________________________________________________________________________

d) Wavelength: ________________________________________________________________________

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Proof that Light is a Wave

Thomas Young demonstrated that light behaves as a wave in the 1800s. He conducted the double slit

experiment shown below:

Predict what the light will look like on the second screen by drawing it in below.

My Prediction

The Experiment Result

Watch The Original Double Slit Experiment on Youtube at https://www.youtube.com/watch?v=Iuv6hY6zsd0 or on your teacher’s Weebly for the results. Don’t cheat! Predict first, then watch!

The double slit experiment shows that light behaves like waves because

Second screen

Light ray shining towards first

screen

First screen with two narrow slits (holes)

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Mini Activity

1. Find a rope (ex. skipping rope) and secure one end to a table leg (or have a friend hold one end). 2. Take the free end and make a wave by either waving your arm up and down, or side to side.

3. Make two sketches of what the wave looks like when you:

Wave your arm FAST (Wave A) Wave your arm SLOW (Wave B)

a) Which wave from above has a shorter wavelength? _____________

b) Which wave do you suppose carries more energy? _____________

c) If the waves you’ve sketched represent harmful UV rays and harmless radio waves, then the UV rays are represented by wave _______ and the radio waves are represented by wave _______.

d) The frequency of a wave is the number of complete wavelengths that pass a point per second as the wave travels. Which wave has the higher frequency? _____________

e) Fill in the following blanks with “increases” or “decreases”. As the wavelength decreases, the frequency __________________ and the energy of the wave __________________. As the wavelength increases, the wavelength __________________ and the energy of the wave __________________.

Try this interactive learning tool by Earthguide to confirm your answers from the mini activity above. You can find it on your teacher’s Weebly or at this address: http://earthguide.ucsd.edu/eoc/special_topics/teach/sp_climate_change/p_emspectrum_ Interactive.html

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What is Colour?

Research

Isaac Newton discovered that the different colours of light are just different wavelengths of visible light. Use Google to determine the colours of the rainbow and which colours have the shortest and longest wavelengths. Show your findings by colouring in the visible light spectrum below, matching the wavelengths to their correct colour.

The Visible Spectrum

Watch Light: Crash Course Astronomy #24 on Youtube from 0:00 – 3:20 min to summarize this lesson on waves. The video can be found by searching the title, visiting https://www.youtube.com/watch?v=jjy-eqWM38g or visiting your teacher’s Weebly.

Light Behaves as a Particle

Very strangely, light can also act as a particle. What does this mean? It means that when you turn on a flashlight,

out comes a steady stream of little tiny balls that hit and bounce off from a surface. Each tiny ball carries a

certain amount of energy with it and is called a photon.

Light as a wave

Light as a particle

How do we know this? One famous experiment that shows that light behaves as a particle is The Photoelectric

Effect. Basically, it was observed that light can “activate” certain materials, meaning that light can change

certain materials. You have observed this in the dark room. Light changes the photo paper during photography,

but red light in the dark room somehow has no effect. What does this all mean?

Photo paper require a certain amount of energy to “activate”. If light was a wave, then you’d expect that

overtime, the photo paper would collect enough energy from the red light to “activate”, much like how food

gets hotter and hotter the longer it is exposed to microwaves inside a microwave oven. But this is not the case!

You can leave photo paper in red light for hours and nothing would happen.

If light was a particle and each particle holds a specific amount of energy, then it doesn’t matter how many

particles hit the photo paper if each one is too weak to activate the photo paper. It’s like saying that a certain

button on the ground can be pushed if 200 pounds of pressure is placed on it. If you weigh 100 pounds, it

doesn’t matter how many times you stand on that button, it simply won’t be pressed!

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Here’s a video describing how you can see this behaviour at home with laser pointers: https://www.youtube.com/watch?v=50fHb7jR5dc It’s called, Light is a Particle! on Youtube, or you can access it on your teacher’s Weebly.

This strange behaviour of light, that sometimes it acts as a wave, and sometimes a particle, is called the wave-

particle duality of light. Scientists still debate today about it today: is light a wave or particle?

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Chapter 3

3.3

Behaviour of Light On Different Materials and Surfaces

P. 220 - 225 BC Science Connections

Vocabulary & Concepts

reflection absorption transmission refraction

transparent translucent opaque incident ray

Light can be Reflected, Absorbed, Transmitted, or Refracted

Light interacts with different materials and surfaces in four different ways. Do some research and

In the left hand column, summarize what each of these terms mean.

In the middle column, draw an example of where you have seen this in every day life.

In the right hand column, use a ruler to finish the diagram by drawing what happens to the incident rays

when they interact with the surface. Be sure to draw arrows on the resulting rays when needed.

Terms & Definitions A drawing of an example of this type

of interaction

Diagram of parallel light rays involved

in this interaction

Reflection:

Absorption:

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Transmission:

Refraction:

Light Behaves Differently When it Encounters Different Types of Materials

Different materials can be transparent, translucent and opaque. Complete the definitions below and draw how

parallel light rays are affected by these different materials.

Transparent: _______________

__________________________

Example: __________________

Translucent: _______________

__________________________

Example: __________________

Opaque: __________________

__________________________

Example: __________________

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Chapter 3

3.4 Part 1

Reflected Light

P. 230 - 245 BC Science Connections

Vocabulary & Concepts

laws of reflection plane mirror concave mirror convex mirror

incident ray reflected ray normal angle of incidence

angle of reflection

How Light is Reflected in a Plane Mirror

Mini Activity

1. Place a plane mirror vertically along the mirror line and, using the ray box with a single-slit baffle, shine the ray of light along the line set up for you at a 45o angle.

2. Using a ruler, trace the reflected ray. 3. Label the normal, incident ray, the reflected ray, the angle of incidence and the angle of reflection on

your diagram. (Refer to p. 232 of BC Connections for definitions of these concepts).

4. What do the angle of reflection and the angle of incidence have in common? Consider how they are

measured and how they compare to one another.

5. What would the angle of reflection be if the angle of incidence was 30o? _________

6. Why does an expert billiards (pool) player need to understand the laws of reflection to make an

accurate shot?

mir

ror

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Characteristics of Images in Plane Mirrors

Four characteristics of images include:

Location: An image may be the same distance, closer to, or farther from the mirror than the object.

Orientation: An image may be upright or inverted (upside-down)

Size: An image may be the same size as, larger than or smaller than the object.

Type: An image may be real or virtual.

Research Use P. 234-235 in the textbook to help you complete this section.

1. Describe the image that forms in a plane mirror and to differentiate between a real and a virtual image. An Image in a Plane Mirror is…

Location: _______________________________ Orientation: _____________________________

Size: ___________________________________ Type: __________________________________

2. In the space below, draw the image of the candle as the eye would see it. When drawing the reflected light from the image of the candle, use a ruler and draw dotted lines. Finally, draw arrows on the light rays to show the direction of travel.

3. A plane mirror produces an image that is nearly identical to the object. However, there is a

difference: the image is __________________ compared to the object. Draw the reflection of the mountains in the lake to demonstrate a ____________________ in the vertical direction.

object plane mirror

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How Light is Reflected in Concave and Convex Mirrors

Watch Cloud Gate Sculpture in Chicago: Time Lapse on Youtube at http://www.youtube.com /watch?v=GBHrpd26JIw or visiting your teacher’s Weebly. Record at least two observations of how properties of the image in Cloud Gate different from those seen in plane mirrors.

Cloud Gate Sculpture by Anish Kapoor

Observations: Describe two ways that the images in the Cloud Gate are different than if the images were in a plane mirror.

1.

2.

Define the following: Concave: ___________________________________

Converge: __________________________________

Convex: ___________________________________ Diverge: ___________________________________

Different portions of the Cloud Gate are concave and other portions are convex. Can you identify them?

Mini Activity: Playing with Concave Mirrors

In this diagram,

PREDICT how

the lines will

look like after it

hits the mirror

using a ruler.

In the diagram,

draw your

RESULTS using a

ruler. Label the

focal point.

Summary: In a ____________________ mirror, light rays _________________________ at a focal point concave / convex converge / diverge

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Mini Activity: Playing with Concave Mirrors

Images in curved mirrors are never identical to the objects they are reflecting. In a concave mirror, the properties of the image depend on the location of the object relative to the focal point.

In the 3 situations below, draw your prediction of the image that is reflected in a concave mirror.

Draw the theoretical results by drawing two light rays using a ruler from the top of the object. See below for more instructions.

Instructions for theoretical results:

1. The first light ray is parallel to the normal, and its reflected ray passes through the focal point. 2. For the first and second diagram, the second light ray passes through the focal point and its reflected

ray is parallel to the normal. For the third diagram, the second light ray meets the mirror at the normal and is reflected at the same angle. You will have to extend these rays using dotted lines behind the mirror to find the image.

3. Where these two light rays meet, draw the reflected image.

Summarize your findings by choosing the correct words from the word pairs to complete the sentences:

smaller/larger inverted/upright real/virtual

In a concave mirror, a distant object past the focal point produces a(n) ____________ ____________ image that is ________________. In a concave mirror, an object closer to the focal point (but not between the focal point and the mirror) produces a(n) __________________ ___________________ image that is _____________.

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Mini Activity: Playing with Convex Mirrors

In this diagram,

PREDICT how

the lines will

look like after it

hits the mirror

using a ruler.

In the diagram,

draw your

RESULTS using a

ruler. Label the

focal point.

Summarize your findings by choosing the correct words from the word pairs to complete the sentence:

In a __________________________ mirror, light rays _____________________ at the focal point. concave / convex converge / diverge

Research

Use P. 239 in the textbook to help you describe the image that forms in a convex mirror. Describe the image formed in a convex mirror in terms of the following properties:

Location: __________________________________ Orientation: ________________________________

Size: ______________________________________ Type: ______________________________________

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Chapter 3

3.4 Part 2

Refracted Light

P. 246-259 BC Science Connections

Vocabulary & Concepts

lens converging lens diverging lens

Light Changes Direction and Speed When it Moves From One Medium to Another

Mini Activity

1. Fill a beaker or glass with water and place a pencil in it.

2. Look at the beaker or glass from the side and draw your observations below.

Express your observations in words. Is the edge of the pencil

one straight line?

3. When light travels from one medium to another, for example, from air to water, its path refracts (bends). What do you THINK causes this refraction? (You do not have to be right, this is a prediction).

4. Read P. 248 in the text and look at Figure 3.37 on P. 249. In the space below, complete the diagram

by drawing the refracted light ray and an explanation of why refraction occurs.

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5. When light travels from air to water, does the refracted ray bend towards or away from the normal?

6. What do you THINK will happen when light travels from water to air – would the refracted ray bend

towards or away from the normal? (You don’t have to be right, this is a prediction).

7. Look at the diagram below showing a fisherman trying to harpoon a fish for dinner.

a) Draw the normal in the diagram below. Remember that the normal is perpendicular to the

line separating the two mediums.

b) Is the light travelling from the fish to the eye of the fisherman bending towards or away from

the normal?

c) How would you advise the fisherman to increase the likelihood they will spear the fish?

Summary: When light travels from a ____________ dense to a _________ dense medium, the ray bends more / less more / less

_______________ the normal. Conversely, when light travels from a _________ dense to a _________ towards / away from more / less more / less

dense medium, the ray bends _______________ the normal. towards / away from

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Light Refracts as it Passes Through Lenses

What is a lens? Define it: _______________________________________________________________________

Mini Activity: Making a Simple Lens

1. Obtain a 10 cm by 10 cm piece of transparent material, a sheet of newspaper, a medicine dropper and some water.

2. Lay the transparent material on the newspaper. Place one drop of water on the transparent material. Draw the shape of the water drop in the observations table below.

3. Choose a word on the newspaper and place the drop of water over it. Compare how the word looks through the drop and without it. Draw your observations in the table below.

4. Add three more drops of water to the first drop of water. Observe the shape of the water drop. Draw the shape of the water drop in the table below.

5. Observe the same word through the larger amount of water. Draw your observations in the table below. Table 1: Observations of the water lens.

Number of Drops of Water

Shape of the water drop Observation of word in newspaper

0 --------------

1

4

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Research

Find 4 different examples of lenses that are used in every day life and draw them below.

Mini Activity: Playing with Converging Lenses

In this diagram, PREDICT how the lines will look like after it hits the lens using a ruler.

In the diagram, draw your RESULTS using a ruler. Label the focal point.

Summarize your findings by choosing the correct words from the word pairs to complete the sentence:

In a _______________________ lens, parallel light rays _____________________________ the focal point. converging / diverging come together at / spread out from

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Mini Activity: Diverging Lenses

In this diagram, PREDICT how the lines will look like after it hits the lens using a ruler.

In the diagram, draw your RESULTS using a ruler. Label the focal point.

Summarize your findings by choosing the correct words from the word pairs to complete the sentence:

In a _______________________ lens, parallel light rays _____________________________ the focal point. converging / diverging come together at / spread out from

What characteristic makes one lens converging and another diverging?

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CHALLENGE Mini Activity

1. Get a tall drinking glass.

2. Get a flash card or a small piece of paper and with a marker draw two arrows, pointing in the same

direction. See below for an example.

3. Lean the card behind the glass so that you can see the arrows through the glass.

4. Slowly fill the glass with water and draw what you see in the table below.

Empty Glass

When water covers the bottom

arrow

When water covers both

arrows

5. To understand why this happened, see if you can figure out the direction of light rays as they travel

from air, through glass, through water, through glass, and finally through air to your eyes. The

diagram below is a top-down view of the glass of water. Draw an incident ray from the tip of the

arrow, and from the bottom of the arrow, travelling towards the glass.

Air

Water

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Chapter 3

3.5

Applications

P. 252-255 BC Science Connections

Vocabulary & Concepts

near sightedness far sightedness refracting telescope reflecting telescope

Refraction Plays a Role in Human Vision

Research

How do the two components of the eye involved with refracting light ensure that a focused image is formed at the back of the eye? Read P. 252 to find out. Colour and label both of these components in the diagram of the eye.

1. The ___________________ causes about _____% of refraction as light passes through this component of the eye.

2. The ___________________ causes about _____% of the refraction as light passes through this component of the eye. However, this component is responsible for focusing on close objects.

Near Sighted and Far Sighted

Watch Farsightedness vs. Nearsightedness, An Explanation at https://www.youtube.com/watch?v=1l8fPLqaIZk Youtube, or you can access it on your teacher’s Weebly.

Try this interactive learning tool by Acuevue to learn about vision problems. You can find it on your teacher’s Weebly or at this address: www.acuvueprofessional.com/virtual-eye-model

Near Sighted Far Sighted

What it looks like

(draw the light rays from the

arrow into the eye)

Medical term

Where is the focal point?

Objects that are near appear…

Objects that are far appear…

Type of corrective lens needed

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Case Study

Patient 1: A 56 year old female is having trouble reading books. She plays violin and has no problem reading the sheet music on her music stand.

1. What vision problem does she have? ____________________________________________________

2. Explain the cause of the problem.

3. Draw a diagram of what the light rays are doing in her eye.

4. Recommend the type of lens that would correct the problem.

Before watching the video below, how do you think laser eye surgery works to correct near sightedness and far

sightedness?

Watch How it’s Made – Laser Eye Surgery at https://goo.gl/xzssK3 on Youtube, or you can access it on your teacher’s Weebly.

Watch Google Working on Smart Contact Lenses at http://www.youtube.com/watch?v=3aeAt9oLsN4 on Youtube, or you can access it on your teacher’s Weebly.

Watch Samsung Smart Contact Lenses at http://www.youtube.com/watch?v=Q3pRjj18ToA on Youtube, or you can access it on your teacher’s Weebly.

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Investigation: How do Telescopes Work?

Use the following website to find out how telescopes work: http://www.bbc.co.uk/science/0/20937803 Refracting Telescopes: use ____________________(mirror/lens) to magnify the image.

1. In your own words, describe how a refracting telescope works.

2. What is one problem of a refracting telescope?

Reflecting Telescope: use ____________________ (mirror/lens) to magnify the image.

3. In your own words, describe how a reflecting telescope works.

4. Where is a better location for a telescope: on Earth or in space? Justify your answer.