# LET Reviewer - PHYSICAL SCIENCE (OPTICS)

Majorship LET Reviewer

 LET Reviewer for Physical Science
PRACTICE TEST IN PHYSICAL SCIENCE (OPTICS)

1. Which of the following is Sir Isaac Newton’s theory that explains light as a particle?
a. Corpuscular Theory
b. Electromagnetic Wave Theory
c. Quantum Theory
d. Wave Theory

2. When light hits a smooth surface, it is
a. bent around corners
b. polarized
c. reflected
d. refracted

3. A ray of light is reflected from a plane mirror. The angle of incidence is 20 degress. The angle between the incident and the reflected ray is
a. 10 degrees
b. 20 degrees
c. 30 degrees
d. 40 degrees

4. What kind of mirror is used in automobile and trucks to give the driver a wider area and smaller image of the traffic behind him/her?
a. concave mirror
b. convex mirror
c. plane mirror
d. none of these

5. The image in a plane mirror is always
a. erect but reversed.
b. erect but not reversed.
c. inverted and reversed.
d. inverted but not reversed.

6. When rays parallel to the principal axis of a concave mirror are reflected, they pass through
a. any point on the axis..
b. the principal focus.
c. the center of curvature of the mirror.
d. the point halfway between the focus and the mirror.

7. A stick partly submerged obliquely in water appears to be bent at a point where it enters the water surface. Which one of the following gives explanation for this observation?
a. Dispersion of light on entering water
b. Light does not travel in straight line in water.
c. Diffraction of light by the surface of the water
d. Refraction of light due to differences in speed of light in air

8. The principle involved in the formation of images on lenses is
a. aberration.
b. dispersion.
c. reflection.
d. refraction.

9. A diamond is a brilliant gem because
a. it has low index of refraction.
b. it has big critical angle.
c. most of the light is refracted.
d. most of the light is reflected internally.

10.When light travels from air to glass its speed
a. increases.
b. decreases.
c. remains the same.
d. increases then decreases.

11.The property of light responsible for the formation of colors is
a. amplitude.
b. quality.
c. velocity.
d. wavelength.

12.Which of the following statements is NOT true about the dispersion of sunlight by a prism?
a. The color most bent is red.
b. White light consists of waves of varying length.
c. Different wavelengths travel with different speed.
d. Different wavelengths correspond to different colors.

13.After a rainstorm, a rainbow may appear in the sky. Which statement explains this observation?
a. Raindrops act as prisms separating sunlight into colors.
b. The white clouds are actually prisms composed of different colors.
c. The colors of the rainbow come from raindrops in the atmosphere.
d. When the sunlight is reflected by the ground towards the clouds, it separates into different colors.

14.A piece of coal appears black when viewed in sunlight because it __________ all the light that falls on it.
a. absorbs
b. disperses
c. reflects
d. transmits

15.A red rose appears red because of its ability to
a. absorb the red color and reflect all others.
b. reflect the red color and absorb all others.
c. transmit all colors except red.
d. transmit the red color and reflect all others.

16.Diffraction of light means that
a. light is a transverse wave.
b. light is reflected from a film.
c. light bends as it enters a different medium.
d. light bends as it passes through a small opening.

17.The sun appears to be more reddish at sunset than at noon. Which of the following phenomena is responsible for this effect?
a. dispersion
b. interference
c. reflection
d. scattering

18.Which property of light produces bright and dark bands on a screen after light from a source passes through two very narrow slits that are near each other?
a. dispersion
b. interference
c. polarization
d. refraction

19.When sunlight falls on soap bubble, the band of colors seen is due to
a. dispersion.
b. interference.
c. pigments of soap.
d. refraction.

20.Polarization of light is an evidence that light
a. is a transverse wave.
b. is a longitudinal wave.
c. has a particle property.
d. wave can destructively interfere with each other.

21. The theory that explains light as a particle.
a. corpuscular theory
b. electromagnetic wave theory
c. quantum theory
d. wave theory

22. When we see a tree, the light that reaches our eyes
a. has been reflected by the tree.
b. has been refracted by the tree.
c. has been separated into a spectrum by the tree.
d. has undergone interference in passing through the tree.

23. Enlarged image can be formed by
a. concave mirrors only
b. convex mirrors only
c. either concave or convex mirror
d. neither concave nor convex mirror

24. The image formed by a convex mirror is always
a. real
b. inverted
c. bigger than the object
d. smaller than the object

25. If you are looking obliquely on a fish under water, in what direction should you aim your arrow to hit it?
a. above the fish
b. below the fish
c. directly to the fish
d. either below or above the fish

26. The term refraction refers to
a. the bending of light rays when they strike a mirror.
b. the bending of light rays when they enter a different medium.
c. the fact that white light is made up of many colors.
d. the fact that light travels in straight line in uniform medium.

27. As the angle of incidence increases, the index of refraction of a medium
a. increases
b. decreases
c. remains unchanged
d. none of the above

28. If you look down on a pool of still water, you see your face clearly. Which one of the following gives the best explanation for this observation?
a. Dispersion of light on entering water
b. Reflection of light by the surface of the water
c. Refraction of light by the surface of the water
d. Light is reflected from the surface of the water in different directions.

29. A diamond is a brilliant gem because
a. it has low index of refraction.
b. it has big critical angle.
c. most of the light is refracted.
d. most of the light is reflected internally.

30.A ray of light is reflected from a plane mirror. The angle of incidence is 30 degrees. The angle between the incident and the reflected ray is
a. 40 degrees
b. 60 degrees
c. 50 degrees
d. 70 degrees

31.When you stand 3 meters in front of a full length mirror, your image is
a. real and 1 meters behind the mirror
b. real and 3 meters behind the mirror
c. virtual and 2 meters behind the mirror
d. virtual and 3 meters behind the mirror

32.The bottom of a clear and deep lake appears to be shallow because of ____________
a. diffraction
b. polarization
c. reflection
d. refraction

33.When sunlight strikes raindrops, it passes through them and produces
a. halo
b. heat
c. rainbow

34.Side mirrors of motor vehicles allow the driver to see wider areas. What best describes the images compared to the real object in this kind of mirror?
a. bigger
b. smaller
c. the same
d. inverted

35.What do you call the separation of light into its component colors?
a. dispersion
b. polarization
c. reflection
d. refraction

36.Where does light travel fastest?
a. air
b. glass
c. vacuum
d. water

37.What do you call the bending of light around the corners of objects?
a. diffraction
b. dispersion
c. reflection
d. refraction

38.A beam of light traveling in air enters a glass medium. What changes does it undergo?
a. change in speed only
b. change in frequency only
c. change in wavelength only
d. change in both speed and wavelength

39.Which is the color of visible light with the longest wavelength?
a. blue
b. red
c. violet
d. yellow

40.Which of the following is a good description of a polarized light?
a. It is an ordinary light.
b. It is a transverse wave.
c. It is a longitudinal wave.
d. It is a wave that vibrates in all directions.