Exam
7a
Name___________________________________
MULTIPLE CHOICE.
Choose the one alternative that best completes the statement or answers the question.
1) I am wearing glasses to correct my nearsightedness. Which of the following statements most
accurately describes the lenses in my glasses?
A) The radii of the two sperical lense surfaces must have opposite sign.
B) The radii of the two spherical lense surfaces must be equal but have opposite sign.
C) The radii of the two spherical lense surfaces must be equal and same sign.
D) The radii of the two spherical lense surfaces must be such as to provide for a negative focal
length.
E) The radii of the two spherical lense surfaces must be same sign but different size, with the
larger radius being closer to my eye.
1)
2) You are projecting 35mm slides onto a wall 2.6m from the projector whose single lens has focal
length 12.0cm.
(a)
How far should the slides be from the lens?
(b) How big will the image be?
A) (a)12.6cm
(b) 72cm
B) (a) 12.6cm (b) 72cm
C) (a) 25cm (b) 36cm
D) (a) 25cm (b) 36cm
2)
3) What is the focal length of a concave mirror if an object placed 50cm in front of the mirror has a
real image 200cm from the mirror?
A) 20cm
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 Spring '05
 wurthmeir

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