The Wave Equation

Question 1

Wave motion

Answer 1

§ Is an activity that carriers energy from one place to another through a medium without actually moving any matter
§ A wave transports energy and not matter

Question 2

Energy Transfer Sound

Answer 2

In sound waves, energy is transferred through the vibration of air particles or particles of a solid through which the sound travels

Question 3

Energy Transfer Light

Answer 3

§ Modern theories say that light behaves like a wave and a particle
§ Wave model is used to explain how light moves/travels and how it interacts with objects at macroscopic levels

Question 4

Sound Requires Particles

Answer 4

§ If there are no air particles to vibrate then the sound wave cannot travel and no sound will be heard
§ Mechanical wave
□ Requires a medium to propagate (move or travel and is used when describing wave motion) and therefore cannot propagate through a vacuum

Question 5

Mechanical Wave - Water Waves

Answer 5

§ Strong winds generate water waves in the deep ocean by strong winds
§ Waves can transport the wind energy to shore by moving subsequent water particles up and down
§ Each water particle stays in the same location in the deep ocean

Question 6

Two different groups

Answer 6

• Transverse
• Longitudinal

Question 7

Transverse Waves

Answer 7

• Motion of the individual particles in the medium is perpendicular to the motion of the wave
• E.g.
  ◊ Water ripples

Question 8

Longitudinal waves

Answer 8

• Motion of the individual particles in the medium is parallel to the motion of the wave
• A longitudinal wave propagates by changing the pressure of the medium
• Compression
  ◊ Region where many particles come together and there is higher than normal pressure
• Rarefaction
  ◊ Region where many particles are spread apart and there is lower than normal pressure
• E.g.
  ◊ Sound waves

Question 9

Displacement/Distance Graph

Answer 9

□ A displacement-distance graph shows the displacement of all particles from their undisturbed or resting positions, along with the length of the wave at a particular point in time
□ y -axis
® Displacement of the particles
□ x-axis
® Distance from the source of the wave

Question 10

Amplitude

Answer 10

• Symbol = (A)
• The maximum displacement of a particle from its resting position
• Can be identified from the displacement-distance graph as the vertical distance from the x-axis to the crest or trough in a wave

Question 11

Wavelength

Answer 11

• Symbol = (λ)
• The distance between two consecutive proportional positions in a wave

Question 12

Displacement/Time Graph

Answer 12

□ A displacement-time graph follows the motion of an individual particle in the wave and shows its displacement from its resting position over time
□ Wave period symbol = (T)
- Time it takes to complete one cycle (wavelength) of a wave
□ Wave frequency symbol = (f)
- The number of wavelengths passing any given point each second
- 1Hz = 1 wavelength passing each second
□ Frequency and period
- Frequency (f) = the inverse of the wave period (T)
- T=1⁄f and f=1⁄T

Question 13

Wave Speed

Answer 13

§ Symbol = (v)
§ The rate at which the wave covers distance
§ Measured in m/s
§ The speed of a wave remains constant while travelling in the same medium
§ Speed = distance/time
□ v=f × λ

Question 14

Communicating With Waves

Answer 14

• Cell phones
• Mobile phones communicate by transmitting radio waves through a network of fixed antennas called base stations