Difference between revisions of "AY Honors/Optics/Answer Key"

Revision as of 00:12, 6 February 2007

The opaque projector, epidioscope, epidiascope or episcope is a predecessor to the overhead projector. It displays opaque materials by shining a bright lamp, often limelight, onto the object from above. A system of mirrors, prisms and/or imaging lenses is used to focus an image of the material onto a viewing screen. Because they must project the reflected light, opaque projectors require brighter bulbs and larger lenses than overhead projectors. Care must be taken that the materials are not damaged by the heat generated by the light source. Opaque projectors are not as common as the modern "overhead".

Opaque projectors are typically used to project images of book pages, drawings, mineral specimens, leaves, etc. They have been produced and marketed as artists’ enlargement tools to allow images to be transferred to surfaces such as prepared canvas, or for lectures and discourses. In the early and middle parts of the 20th century, low-cost opaque projectors were produced and marketed as toys for children.

External links

Episcopes and epidiascopes, photographs of a collection.
Historic Ross Epidiascope
Brief description of the modern Braun Paxiscope XL Epidiascope.
Another description of the Braun Paxiscope unit.
Digital epidiascope from Samsung.

de:Episkop pl:Episkop

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-{{honor_header|2|1962|Health & Science<br>General Conference<br>2001 Edition}}
+The '''opaque projector''', '''epidioscope''', '''epidiascope''' or '''episcope''' is a predecessor to the [[overhead projector]]. It displays opaque materials by shining a bright lamp, often [[limelight]], onto the object from above. A system of mirrors, prisms and/or imaging [[Lens (optics)|lenses]] is used to focus an image of the material onto a viewing screen. Because they must project the reflected light, opaque projectors require brighter bulbs and larger lenses than overhead projectors. Care must be taken that the materials are not damaged by the heat generated by the light source. Opaque projectors are not as common as the modern "overhead".
-==1. Define and/or draw a diagram of the following:==
-;a. Focal length :
-;b. Positive lens :
-;c. Negative lens :
-;d. Two kinds of distortion:
-;e. Longitudinal color:
-;f. Lateral color:
-;g. Spherical aberration:
-;h. Achromatic lens :
-;i. Refraction of light:
-==2. Explain how light behaves when it strikes or traverses water, oil, feldspar, and a mirror.==
-==3. Name and draw diagrams of three kinds of positive lenses and three kinds of negative lenses.==
-==4. What should be the minimum distance of light source from the lens when testing for focal length?==
-==5. Find the focal length of at least four lenses, one being a negative lens.==
-==6. Explain by diagram why an image from a positive lens makes an image reversed and inverted.==
-==7. Show with diagrams how a prism works. State the angles at which the colors appear and disappear.==
-==8. Show and demonstrate what happens when light strikes one-way glass.==
-==9. Construct one optical instrument using mirrors or lenses, such as a periscope, a slide or opaque projector, or a simple telescope.==
-==10. Explain what is meant by the term 6<math>\times</math>35 and 7<math>\times</math>50 as applied to binoculars.==
-The numbers used for describing binoculars give the power followed by the diameter in milimeters. This means that 6<math>\times</math>35 have a magnifying power of 6x and have a diameter of 35.
+Opaque projectors are typically used to project images of book pages, drawings, mineral specimens, leaves, etc. They have been produced and marketed as artists’ enlargement tools to allow images to be transferred to surfaces such as prepared canvas, or for lectures and discourses. In the early and middle parts of the 20th century, low-cost opaque projectors were produced and marketed as toys for children.
-The power represents how much bigger the object appears than with the unaided eye. You can also think of how many times closer it appears to be. The diameter lets you know how much light is gathered by the lens. A 50mm objective lens gathers much more light than a 35mm objective lens. Because the amount of light goes up by area we can calculate the light gathering difference as follows:
+==See also==
+* [[Projector]] for a directory of projector types.
-Area of lens= π  (radius of lens)<math>^2</math>
+==External links==
-{| border ="2"
+* [http://www.luikerwaal.com/newframe_uk.htm?/epidia_uk.htm Episcopes and epidiascopes], photographs of a collection.
-|+Numbers that Describe Binoculars
+* [http://www.curzon.org.uk/collection/Epidiascope.html Historic Ross Epidiascope]
-| Binocular Specification || Magnifying Power || Diameter of objective  (mm) || Area of objective <math>mm^2</math> || Light gathering power (compared to unaided eye)
+* [http://adverlab.blogspot.com/2005/03/tools-epidiascope.html Brief description] of the modern [[Braun]] Paxiscope XL Epidiascope.
-|-
+* [http://www.firstcall-photographic.co.uk/pp/Projectors/35mm_Projectors_and_Epidiascopes/Braun_Paxiscope_XL_Epidiascope.html Another description] of the Braun Paxiscope unit.
-|Unaided Eye || 1x || 8|| 50.265|| 1x
+* [http://adverlab.blogspot.com/2005/06/epidiascope-strikes-back.html Digital epidiascope] from [[Samsung]].
-|-
-|10x25 || 10x || 25 || 490.8738 || 9.7x
-|-
-|6x35 || 6x || 35 || 962.11275 || 19.14x
-|-
-| 7x50 || 7x || 50 || 1,963.495 || 39.06x
-|-
-|}
+[[Category:Projectors]]
-The 50mm objective lens collects 2.0408... times more light than a 35mm objective lens. If you are in a dark environment, you will get twice as much light with the 7x50 binoculars than with a 6x35. The only real disadvantage is that the 7x50 binoculars are heavier to carry as well because of the increase in size.
+[[de:Episkop]]
+[[pl:Episkop]]
-==11. Define the term "f/stop" as used in connection with cameras. What does it mean when a lens is fast or slow? Is an f/8.5 lens faster or slower than an f/8 lens?==
-==References==
-[[Category:Adventist Youth Honors Answer Book]]