End Of Unit Test

Question 1

Which word describes the meaning of “plane” in the context of a plane mirror?
- Options: flat, irregular, round, smooth

Answer 1

Flat

Question 2

Copy and complete the sentence that describes how light is reflected from a plane mirror.
- Sentence: The angle of reflection is … to the angle of ….

Answer 2

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

Question 3

What should be included in a diagram showing how light is reflected from a plane mirror?
- Instructions: Label the reflected ray and the angles of incidence and reflection. You do not have to measure angles.

Answer 3

The diagram should include:
- The normal (a line perpendicular to the mirror surface).
- The incident ray (the incoming light ray).
- The reflected ray (the light ray bouncing off the mirror).
- The angle of incidence (between the incident ray and the normal).
- The angle of reflection (between the reflected ray and the normal).

Question 4

Why are mirrors fitted on a motorcycle?

Answer 4

The mirrors allow the motorcycle rider to see objects that are behind the motorcycle, enhancing safety by providing a view of the rear.

Question 6

Draw a ray diagram to show how the rider can see a ray of light coming from behind.

Answer 6

The diagram should include:
- The light ray coming from behind the motorcycle.
- The light ray reflecting off the mirror.
- The reflected ray entering the rider’s eyes.
- Label the incident ray, reflected ray, and the angles of incidence and reflection.

Question 7

What is the name given to light changing direction when it passes from air into water?

Answer 7

Refraction

Question 8

Complete the sentences with either ‘speeds up’ or ‘slows down’:
- a. When light passes from air into glass, the light … .
- b. When light passes from air into water, the light … .
- c. When light passes from glass into air, the light

Answer 8

• a. slows down
  
  • b. slows down
  • c. speeds up

Question 9

Write T or F after each statement to show if it is true or false:
- In a ray diagram, the angle of incidence is measured between the light ray and the surface.
- In a ray diagram, the angle of refraction is measured between the light ray and the normal.
- In a ray diagram, the normal is a line at 90° to the surface.

Answer 9

• F (The angle of incidence is measured between the light ray and the normal.)
  
  • T
  • T

Question 10

Copy the ray diagrams to show what happens to the light rays. On each diagram, draw and label:

• The normal
• The refracted ray
• The angles of incidence and refraction

Answer 10

The diagrams should include:
- A normal line at 90° to the surface.
- The incident ray entering the new medium (water or glass).
- The refracted ray bending towards or away from the normal, depending on the medium.
- Label the angles of incidence and refraction.

Question 11

Complete the sentences using words from the list:
- White light can be split into its component … .
- This is called … and can be done with a … .
- The range of colours is called a … .
- The range starts with red and ends with … .

Answer 11

• White light can be split into its component colours.
  
  • This is called dispersion and can be done with a prism.
  • The range of colours is called a spectrum.
  • The range starts with red and ends with violet.

Question 12

Describe the light that will emerge at points A, B, and C when white light shines on each of these filters:
- a. White light through a red filter.
- b. White light through a blue filter and then a red filter.
- c. White light through a green filter.

Answer 12

• a. Red light will emerge at point A.
  
  • b. No light will emerge at point C (since the blue filter blocks red light, and the red filter blocks blue light).
  • c. Green light will emerge at point B.

Question 13

Write the color that each of these objects will appear:
- a. A red book in white light.
- b. A green door in green light.
- c. A white T-shirt in blue light.
- d. A blue ball in green light.

Answer 13

• a. Red
  
  • b. Green
  • c. Blue
  • d. Black (since the blue ball absorbs green light and reflects no light)

Question 14

Color Mixing with Lights**
- Question: Write the colors that will be seen at the points X, Y, and Z when two different colored lights of the same brightness shine onto a white wall and overlap:
- a. Red light and blue light.
- b. Green light and blue light.
- c. Red light and green light.
- d. State the color that would be seen if red, green, and blue lights of the same brightness all overlapped on the white wall.

Answer 14

• a. Magenta (red + blue)
  
  • b. Cyan (green + blue)
  • c. Yellow (red + green)
  • d. White (red + green + blue)