Waves, Sound & Light

Question 1

Define a vibration

Answer 1

The repetition of a pulse

Question 2

Define a pulse

Answer 2

A single disturbance

Question 3

Give one example of a transverse wave

Answer 3

(Any one of these answers apply)

• Light
• Waves in the ocean

Question 4

Give an example of a longitudinal wave

Answer 4

Sound

Question 5

In which of the following does sound travel the fastest?

a) Solids
b) Liquids
c) Gases
d) Vacuum

Answer 5

a) Solids

Question 6

Explain why sound can not travel in outer space

Answer 6

There are no particles to carry the waves

Question 7

By which aspect of a soundwave is the volume of the sound determined?

Answer 7

The amplitude of the wave

Question 8

State the audible sound frequency for humans

Answer 8

20 - 20,000 Hz

Question 9

Describe how humans are able to hear sounds

Answer 9

Sound travels in a wave form, meaning the vibrations are passed from one particle on to the next. Once these vibrations reach the human ear, the eardrum starts to vibrate at different frequencies, which the brain then converts into different sounds

Question 10

Describe how one can calculate the distance of an object using echos

Answer 10

Sound travels at 330 m/s through air. To calculate the distance between the source and the echo, simply divide the time taken to hear the echo by two, and multiply this number by 330 to get the distance in meters. For example, if an echo is heard 4 seconds after shouting to a building, the time taken for the echo to reach the building is two seconds, 2 x 330 = 660 meters away. Ta-da! Now you can also pretend to be a smartass!

Question 11

Name two properties of the image formed by a pinhole camera

Answer 11

• Inverted

- Real

Question 12

Name five properties of an image formed in a plane mirror

Answer 12

• Virtual
• Upright
• Laterally inverted
• Same size as object
• Equidistant

Question 13

State the law of reflection

Answer 13

The angle of incidence is equal to the angle of reflection

Question 14

Describe 5 advantages of reflection

Answer 14

• Mirrors
• Dentists and doctors use mirrors
• Rearview mirrors
• Kaleidoscopes
• Periscopes

Question 15

Name three disadvantages of reflection

Answer 15

• Danger of reflection on a wet road
• Fog and mist
• Light inside a camera can spoil the picture

Question 16

Describe three applications of reflection

Answer 16

• Reflectors (Concave mirrors used in torches)
• Make-up, shaving and dental mirrors (Concave mirror enlarges image
• Driving mirrors (Convex mirror provides a wider field of view)

Question 17

Define refraction

Answer 17

The bending of light when it passes from one medium to another

Question 18

Name the colours into which white light is broken up when refracted through a triangular glass prism, from the colour appearing at the top to the colour appearing at the bottom

Answer 18

RED
ORANGE
YELLOW
GREEN
BLUE
INDIGO
VIOLET

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