Optics Without MathematicsSociety for promoting Christian knowledge, 1883 - 124 páginas |
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Página 26
Thomas William Webb. Principal Focus . Here the image of the sun will always be formed . The distance from it to C , or to the surface ( both equal ) , is called the Focal Length of the mirror ; it is of course half the radius . If R ...
Thomas William Webb. Principal Focus . Here the image of the sun will always be formed . The distance from it to C , or to the surface ( both equal ) , is called the Focal Length of the mirror ; it is of course half the radius . If R ...
Página 32
... focal length would form an image of the Sun 1 inch in diameter1 , in which the heat would exceed the ordinary solar heat in the proportion of 12 to 722 , more than 5000 times , and as in putting the solar heat as low as 100 ° Fahrenheit ...
... focal length would form an image of the Sun 1 inch in diameter1 , in which the heat would exceed the ordinary solar heat in the proportion of 12 to 722 , more than 5000 times , and as in putting the solar heat as low as 100 ° Fahrenheit ...
Página 51
... focus , real or virtual as the case may be . The focus for parallel rays is PF , and its distance from the lens is the focal length , or as it is frequently ex- pressed , the focus of the lens . As the rays may pass through the lens ...
... focus , real or virtual as the case may be . The focus for parallel rays is PF , and its distance from the lens is the focal length , or as it is frequently ex- pressed , the focus of the lens . As the rays may pass through the lens ...
Página 53
... lens of ordinary glass this will bring P PF out PF at about the distance of the radius , a convenient but accidental coincidence ; with a denser medium , as diamond , the focal length with the same radii would be shorter ; longer , with ...
... lens of ordinary glass this will bring P PF out PF at about the distance of the radius , a convenient but accidental coincidence ; with a denser medium , as diamond , the focal length with the same radii would be shorter ; longer , with ...
Página 54
... lens split in two edgeways . What will result ? Two plano - convex lenses , each half as deep , or strong , that is , having half as much refraction , and therefore about twice the original focal length , which will not be affected by ...
... lens split in two edgeways . What will result ? Two plano - convex lenses , each half as deep , or strong , that is , having half as much refraction , and therefore about twice the original focal length , which will not be affected by ...
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Términos y frases comunes
angles of incidence aperture axis beautiful called candle circle cloth boards colour concave lens concave mirror conjugate foci converging convex lens course crossing crystal crystalline lens curious curves dark direction dispersion distance Double Refraction edge equal angles equi-convex eye-lens Fcap feet focal image focal length form an image fraction front happens hole inches larger lenses look looking-glass magnifying power microscope minute moon Newtonian reflector NORTHUMBERLAND AVENUE object object-glass opposite optical parallel rays perfect perfectly picture plane mirror polarised position prism produce PROMOTING CHRISTIAN KNOWLEDGE properties of light proportion radiant radius rainbow ray passes reflected rays reflecting telescopes refraction retina reverse right angles seen shorter focus side sideways sine Sir EDMUND BECKETT spectrum speculum sphere spherical spherical aberration straight line suppose surface telescope thing tion turned undulations violet waves wonderful
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