Physics

Question 1

1An astronomical telescope in normal adjustment has its lenses separated by

Hard

A. one focal length B. the sum of their focal lengths C. zero D. the difference of their focal lengths

Question 2

2A diverging lens has a positive power.

Easy

A. True B. False

Question 3

3What is the focal length of a lens of power −2 D?

Easy

A. −50 cm B. 50 cm C. −0.02 cm D. −20 cm

Question 4

4A diverging (concave) lens always forms images that are

Easy

A. real and inverted B. magnified and real C. virtual, upright and diminished D. at infinity

Question 5

5The image on the retina is inverted.

Easy

A. True B. False

Question 6

6An object is placed 60 cm from a converging lens of focal length 20 cm. Find the image distance.

Hard

A. 80 cm B. 15 cm C. 30 cm D. 40 cm

Question 7

7A converging lens of focal length 40 cm has a power of ___ dioptres.

Easy

Your answer (fill in the blank)

Question 8

8A converging lens can form both real and virtual images.

Easy

A. True B. False

Question 9

9A converging lens of focal length 20 cm has a power of ___ dioptres.

Easy

Your answer (fill in the blank)

Question 10

10The near point of a normal eye is about 25 cm.

Medium

A. True B. False