Deck 24: Optical Instruments

Question 1

Two converging lenses, the first with focal length $10.0 \mathrm{~cm}$ and the second with focal length $20.0 \mathrm{~cm}$ , are separated by $40.0 \mathrm{~cm}$ . An object, $3.00 \mathrm{~cm}$ in height, is placed $30.0 \mathrm{~cm}$ in front of the first lens. Where is the final image formed?

A) $45.0 \mathrm{~cm}$ after the second lens
B) $100 \mathrm{~cm}$ after the second lens
C) $5.00 \mathrm{~cm}$ after the second lens
D) $11.1 \mathrm{~cm}$ after the second lens
E) $5.00 \mathrm{~cm}$ before the second lens

Answer 1

$100 \mathrm{~cm}$ after the second lens

Question 2

Two converging lenses, the first with focal length $10.0 \mathrm{~cm}$ and the second with focal length $20.0 \mathrm{~cm}$ , are separated by $40.0 \mathrm{~cm}$ . An object, $3.00 \mathrm{~cm}$ in height, is placed $30.0 \mathrm{~cm}$ in front of the first lens. Where is the image formed by the first lens?

A) $15.0 \mathrm{~cm}$ after the second lens
B) $7.50 \mathrm{~cm}$ after the second lens
C) $15.0 \mathrm{~cm}$ after the first lens
D) $7.50 \mathrm{~cm}$ after the first lens
E) $55.0 \mathrm{~cm}$ after the second lens

Answer 2

$15.0 \mathrm{~cm}$ after the first lens

Question 3

Two converging lenses, the first with focal length $10.0 \mathrm{~cm}$ and the second with focal length $20.0 \mathrm{~cm}$ , are separated by $40.0 \mathrm{~cm}$ . An object, $3.00 \mathrm{~cm}$ in height, is placed $30.0 \mathrm{~cm}$ in front of the first lens. What is the height of the final image?

A) $1.50 \mathrm{~cm}$
B) $12.0 \mathrm{~cm}$
C) $6.00 \mathrm{~cm}$
D) $3.00 \mathrm{~cm}$
E) $24.0 \mathrm{~cm}$

Answer 3

$6.00 \mathrm{~cm}$

Question 4

Two converging lenses, the first with focal length $10.0 \mathrm{~cm}$ and the second with focal length $20.0 \mathrm{~cm}$ , are separated by $40.0 \mathrm{~cm}$ . An object, $3.00 \mathrm{~cm}$ in height, is placed $30.0 \mathrm{~cm}$ in front of the first lens. Which of the following characteristics does the final image have?

A) real and inverted
B) virtual and inverted
C) real and upright
D) virtual and upright
E) none of these choices are correct

Question 5

Two lenses, the first with focal length $10.0 \mathrm{~cm}$ and the second with focal length $-12.5 \mathrm{~cm}$ , are separated by $20.0 \mathrm{~cm}$ . An object of height $2.40 \mathrm{~cm}$ is placed $15.0 \mathrm{~cm}$ in front of the first lens. Where is the final image?

A) $12.5 \mathrm{~cm}$ after the second lens
B) $20.0 \mathrm{~cm}$ after the second lens
C) $100 \mathrm{~cm}$ after the second lens
D) $50.0 \mathrm{~cm}$ after the second lens
E) $5.60 \mathrm{~cm}$ after the second lens

Question 6

Two lenses, the first with focal length $10.0 \mathrm{~cm}$ and the second with focal length $-12.5 \mathrm{~cm}$ , are separated by $20.0 \mathrm{~cm}$ . An object of height $2.40 \mathrm{~cm}$ is placed $15.0 \mathrm{~cm}$ in front of the first lens. What is the size of the final image?

A) $4.80 \mathrm{~cm}$
B) $12.4 \mathrm{~cm}$
C) $2.40 \mathrm{~cm}$
D) $24.0 \mathrm{~cm}$
E) $0.96 \mathrm{~cm}$

Question 7

Two lenses, the first with focal length $10.0 \mathrm{~cm}$ and the second with focal length $-12.5 \mathrm{~cm}$ , are separated by $20.0 \mathrm{~cm}$ . An object of height $2.40 \mathrm{~cm}$ is placed $15.0 \mathrm{~cm}$ in front of the first lens. Which of the following characteristics does the final image have?

A) virtual and upright
B) real and upright
C) virtual and diminished in size
D) virtual and inverted
E) real and inverted

Question 8

A $50.0 \mathrm{~mm}$ lens is used to take a picture of an object $1.30 \mathrm{~m}$ tall located $4.00 \mathrm{~m}$ away. What is the height of the image on the film?

A) $16.5 \mathrm{~mm}$
B) $21.0 \mathrm{~mm}$
C) $10.5 \mathrm{~mm}$
D) $12.0 \mathrm{~mm}$
E) $9.20 \mathrm{~mm}$

Question 9

A nearsighted person wears contact lenses of refractive power $-6.0 \mathrm{D}$ . What is his far point?

A) $-17 \mathrm{~cm}$
B) $-6.0 \mathrm{~cm}$
C) $6.0 \mathrm{~cm}$
D) $-4.0 \mathrm{~cm}$
E) $17 \mathrm{~cm}$

Question 10

A concave mirror has a radius of $2.0 \mathrm{~m}$ . What is the refractive power of a lens of the same focal length as the mirror?

A) $0.75 \mathrm{D}$
B) $-0.50 \mathrm{D}$
C) $2.0 \mathrm{D}$
D) $1.0 \mathrm{D}$
E) $0.50 \mathrm{D}$

Question 11

The refractive power of a lens of focal length $40 \mathrm{~cm}$ is

A) $-2.5 \mathrm{D}$ .
B) $2.5 \mathrm{D}$ .
C) $0.40 \mathrm{D}$ .
D) $0.16 \mathrm{D}$ .
E) $4.0 \mathrm{D}$ .

Question 12

A lens has a refractive power of $-1.50 \mathrm{D}$ . What is its focal length?

A) $8.50 \mathrm{~cm}$
B) $66.7 \mathrm{~cm}$
C) $-66.7 \mathrm{~cm}$
D) $150 \mathrm{~cm}$
E) $-150 \mathrm{~cm}$

Question 13

For maximum angular magnification in a compound microscope, the objective focal length $\left(f_{o}\right)$ and the eyepiece focal length $\left(f_{e}\right)$ should be chosen so that

A) $f_{o}$ and $f_{e}$ are both the smallest available.
B) $f_{o}$ and $f_{e}$ are about the same.
C) $f_{o}$ and $f_{e}$ are both the largest available.
D) $f_{o}$ is the largest available; $f_{e}$ is the smallest available.
E) $f_{o}$ is the smallest available; $f_{e}$ is the largest available.

Question 14

An astronomical telescope is made with lenses of focal lengths 80.0 and $2.00 \mathrm{~cm}$ . What is the barrel length of this telescope?

A) $105 \mathrm{~cm}$
B) $82.0 \mathrm{~cm}$
C) $80.0 \mathrm{~cm}$
D) $78.0 \mathrm{~cm}$
E) $127 \mathrm{~cm}$