Optics Answers

6 Which of the following is NOT true of experiments involving curved mirrors? a) image distance is negative for for real image b) object distance is positive c) image distance is negative for virtual image d) focal length is negative for convex mirrors
7 An estimate of the refractive index of glass is 1.5. If the angle of incidence is 30o the angle of refraction is? a) 19 o b) 60 o d) 35 o d) 70 o
8 The critical angle for total internal reflection at an air - water interface is approximately 48o. In which of the following situations will total internal reflection occur. a) light incident in water at
40 o b) light incident in water at 55 o c) light incident in air at 40 o d) light incident in air at 55 o
9 When refraction occurs which of the following remains unchanged? a) wave number b) wavelength c) velocity d)frequecy
10 Which of these may NOT be a useful apparatus in an optical experiment? a)optical pins b)lenses c) protractor d) crocodile clip

2 When a virtual image is created in a plane mirror
a) the image is upright. b) the image is located behind the mirror. c)reflected rays diverge. d) all of the above
3 The critical angle for a light from the bottom of a swimming pool shining upward toward the pool's surface is the angle? a) where light is refracted so it just skims the pool surface. b) 43 degrees. c) at which all light is refracted out of the pool. d) 42 degrees.
4 Convex mirrors are mostly used as? a) magnifying glasses b) driving mirrors c) dentist mirrors
d) artist mirrors
5 In an experiment involving a spherical mirror, 1/v was plotted on the vertical axis and 1/u on the horizontal axis. What is the linear magnification? a) slope of the graph b) inverse of the the slope of the graph c) intercept on the vertical axis d) intercept on the horizontal axis

1)Two blocks of masses M=2.0kg and 2M,are connected to a spring of spring constant k= 200 N/m that has one fixed.The horizontal surface and the pulley are frictionless and the pulley has negligible mass.The blocks are released from rest with the spring relaxed.
a)What is the combined kinetic energy of the two blocks when the hanging block has fallen 0.10m?
b)What is the kinetic energy of the hanging block when it has fallen that 0,10m?

Which of these may NOT be a useful apparatus in an optical experiment? A.optical pins B.lenses C.protractor D.crocodile clip

Explain in brief why color of sky and sea or ocean appears to be blue.

20 Light is a form of energy that -------

a. is transported from place to place due to the temperature gradient
b. requires material media for its propagation

c. stimulates the sensation of sight

d. cannot be difrracted

15 How far from a magnifying glass do you place an object to view it?
a.closer than than the focal length
b.distance equal to the focal length
c. greater than the focal length but less than twice the focal length
d. at twice the focal length
16 Telescopes that use mirrors as the objectives are known as -----------
a. refractors

b. reflectors

c. Galilean telescopes

d. terrestial telescopes

17 The property of light waves that detrmines its brightness is its -----------
a. wavelength

b. velocity

c. frequency

d. amplitude

18 The speed of light in glass is approximately ---------- that in air
a. 100 times faster than

b. 100 times slower than

c. 50 per cent faster than

d. 33 percent slower than

19 Which of the following is NOT correct?

a. light is a longitudinal wave

b. light is a tranverse wave

c. light is an electromagnetic wave

d. light can exhibit the phenomenon of polarisation

11 Where is the image located when an object is 60 cm from a convex mirror with a focal length of 20 cm?
a.15 cm behind
b. 30 cm behind
c. 60 cm behind
d. 15 cm in front
12 If the sun is 150 million km away from the earth, how long does it take sunlight to reach the earth
a. 0.5 s
b. 1500 s
c. 45 s
d. 500 s
13 The critical angle for total internal reflection at an air-water interface is approximately 48 degrees. In which of the following situations will total internal reflection occur?
a. light incident in water at 40 dgrees
b. light incident in water at 55 dgrees
c. light incident in air at 40 dgrees
d. light incident in air at 55 dgrees
14 How many diopters are there for for a converging lens with a focal length of 0.4m?
a. −2.5
b. −0.4
c. +0.4
d. +2.5

6 If rays of light parallel and close to the principal axis are incident on a --------- mirror, they converge to a point after reflection from the mirror
a. plane

b. convex

c. concave

d. diffuse

7 What type of mirror would you use to produce a magnified image of your face?

a. plane

b. concave

c. convex

d. diffuse

8 The focal length of a curved mirror is -------- the radius of the spherical surface.
a. twice

b. equal to

c. half

d. one-quater

9 The image formed by a bathroom mirror is
a. erect and virtual
b. erect and real
c.inverted and virtual
d. inverted and real

10 What type of image is formed when an object is placed at a distance of 1.5 focal lengths from a convex mirror?
a. erect and virtual

b. inverted and virtual
c. erect and real

d. inverted and real

1 The human eye employs a -------- lens to -------- images.
a. converging ...... real

b. converging ...... virtual

c. diverging ..... real

d. diverging ..... virtual
2 A camera obscura used by a potrait painter is located 6 m from a child who stands 1 m tall. How tall is her image if the back of the camera obscura is 2 m away?
a. 1/3 m

b. 1/2 m

c. 1 m

d. 3 m
3 The law of reflection states that
a. light travels in a straight line

b. light must be reflected into our eyes to be seen

c. the angle of reflection is equal to the angle of incidence

d. light striking a rough surface is scattered in all directions

4 If you stand 2 m in front of a plane mirror, how far from you is your image?
a. 1 m

b. 2 m

c. 3 m

d. 4 m
5 If a 4-m-tall child stands 2 m in front of a vertical plane mirror, the image of the child will be ------- m tall
a. 1

b. 2

c. 3

d. 4