# Fakultät 1: Mathematik, Naturwissenschaften und Informatik ```Fakult&auml;t 1: Mathematik, Naturwissenschaften und Informatik
Lehrstuhl f&uuml;r Physikalische Chemie und Analytik
Dr. Reiner Schmid
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- homework 11 -
1. A concave shaving mirror has a radius of curvature of 35.0 cm. It is positioned so that the
(upright) image of a man&acute;s face is 2.50 times the size of the face. How far is the mirror from
the face?
Results in white letters:
p = 10.5 cm
2. An object is 20 cm to the left of a thin converging lens having a 30 cm focal length. (a)What
is the image distance i? Prove the outcome with a ray diagram. (b) If the lens is a diverging
one of the same focal length, what is the image distance now? Find the image position with
a ray diagram.
Results in white letters:
(a) i = -60 cm
(b) i = -12 cm
3. You produce an image of the sun on a screen, using a thin lens whose focal length is 20.0cm.
What is the radius of the image? (distance Sun-Earth: 1.5*1011 m, Sun&acute;s radius: 6.96*108 m)
Results in white letters:
hi = 9.3*10-4 m (approx. 1mm)
4. A lens is made of glass having a index of refraction of 1.5. One side of the lens is flat, and
the other is convex with a radius of curvature of 20 cm. (a) Find the focal length of the lens.
(b) If an object is placed 40 cm in front of the lens, where will the image be located?
Results in white letters:
(a) f = 40 cm
(b) i = infinity
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