Download Describe how a clear image is formed.

Science 8
6.2 Extending Human Vision
p. 216-225
Name: _____________________
Date: ____________ Block: ____
Brainstorm some reasons you think that human vision might need to be extended?
Look to p. 216 for ideas. _________________________________________________________
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How to Bring an Image into Focus
Describe how a clear image is formed.
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What is focussing and why is it important?
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Microscopes
 Compound light microscopes use __________
_________________ lenses to ___________________
small, close objects
 To ___________________ means to cause to look
_________________ than the real size
 The object to be viewed is placed on a transparent slide and
illuminated from _____________
 The light passes by or ______________ the ___________
object on the ___________ and then ____________
through the __________________ lens
 The objective lens is a ________________ lens and
produces an ___________________ image of the object
 The eyepiece lens is another ________________ lens that
___________________ the image again
 The final image can be ____________________ of times larger than the
_______________ object
Telescopes
 A telescope uses a ____________ or a concave
______________ to gather more of the light from
________________ objects
 As a result, objects appear much ________________
 This allows the image to be ____________________ to
reveal more detail
 To the right is a ____________________ telescope
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Science 8
Name: _____________________
Date: ____________ Block: ____
Explain how a refracting telescope works
_________________________________________________________________________
_________________________________________________________________________
_____________________________________________
_____________________________________________

To the right is a ___________________ telescope
How is this type of telescope different from a refracting
telescope? ____________________________________
____________________________________________
How does this type of telescope work?
_____________________________________________
_____________________________________________
_____________________________________________
_____________________________________________
Binoculars
 Binoculars are actually _________
____________________
__________________ mounted side by side
 These telescopes are shortened by placing
______________ inside that serve as
_____________ __________________
 Rather than travelling down the long ________
of a ______________________, the prisms
reflect the light in binoculars back and forth
inside a __________________ tube
Cameras
Describe how a camera works
_________________________________________________________________________
_________________________________________________________________________
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How are wide-angle lenses and telephoto lenses used for cameras?
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Cameras have Similarities to Human Eyes
 A camera and the human eye have many
similarities
 The lens cap of the camera is similar to the
human ________________
 A diaphragm on a camera is similar to the
________ of the eye
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Science 8

Name: _____________________
Date: ____________ Block: ____
Light passes through the __________ and forms an ___________________ image in both
the _______ and the ______________
How is focussing different in the camera and the human eye?
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What is at the back of a camera?________________________________________________
How is this structure similar to the rods and cones in our eyes? i.e. What function does it serve?
_________________________________________________________________________
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Lasers
 In laser light, all the light has the same _________________________, all the light rays
are moving in the ____________ direction, and all of the _________________ and
____________________ are __________________ up
 Laser light can travel _______________ distances and can contain a lot of _____________
 Laser light ________________ refract into a rainbow because it contains only ________
wavelength of light
Laser Surgery
 Lasers are used for ____________________________________________________
___________________________________________________________________
 Describe some different ways that lasers can be used to correct vision
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Optical Fibres
 An optical fibre is a simple way to __________________ light
 They are ___________________ glass fibres that can ________________ light from one
place to another
 Almost _________ light is ___________ or ___________________ in optical fibres
 Total internal reflection is when all the light rays strike the ___________ of the fibre and
are ____________________ back into it
 Optical fibres are used in medicine to transmit ________________ of the _____________
of a person’s body from a tiny ________________ at one end of the fibre optics cable to a
________________ at the other end
What are some uses for fibre optics in telecommunications?
_________________________________________________________________________
_________________________________________________________________________
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Science 8
Name: _____________________
Date: ____________ Block: ____
The Human Eye
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