ᴏᴘᴛɪᴄᴀʟ ɪɴsᴛʀᴜᴍᴇɴᴛs

                37 - 40

Simple Magnifier - most basic

single converging lens

object must be within focal length

viewed from opposite side

virtual, magnified, upright, further away image

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            Microscopes

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lenses combined to increase overall magnifying power

image produced by one lens as object for other lens

compound microscope - two converging lenses

closer to object - objective

closer to observer - eyepiece

object just outside focal length of objective

real, inverted image formed by objective

virtual, magnified, inverted - final image

inventor unknown, first model demonstrated around 1621

17c scientists, including Galileo experiment with multi-lens

object must be at least as large as wavelength of light

400-700nm

electron microscope used for smaller length scales

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             Telescopes

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reflecting telescope - a concave mirror, collect, focus light

Issac Newton credited with assembling first in 1688

1781 - discovery of uranus by William Herschel

Hubble Space Telescope - 2.4m mirror, deployed in 1990

from Space Shuttle Discovery

keck Observatory - Mauna Kea, Hawaii, 2 reflecting 

telescopes, mirror diameter of 10m

refracting telescope - combination of lenses

converging objective lens, light ray reach near parallel

to one another

focused to form real, inverted image at focal point

eyepiece just inside focal point, produce final virtual image

length is sum of focal lengths of objective and eyepiece

useful for viewing larger, brighter objects

large diameter lenses heavy, prone to sagging

refracting lenses more susceptible to chromatic aberration