Features of Waves | Physics for GCSE/IGCSE - Year 11 PDF Download

Waves - Basic

• Waves serve as carriers of both energy and information.
• Waves are characterized as oscillations or vibrations around a fixed point.
  • For instance, ripples induce particles of water to oscillate vertically.
  • Sound waves cause particles of air to oscillate horizontally.
• In all instances, waves transmit energy without transferring material.
  • In the case of water waves, it is the wave itself, not the water, that travels.
  • Similarly, for sound waves, it is the wave itself, not the air molecules, that moves.
• The behavior of floating objects on water offers evidence that waves solely transmit energy, not matter.

Wave Motion

• Wave vibrations can be demonstrated using ropes (transverse) and springs (longitudinal).

Demonstrating Wave Motion

• Characteristics of waves, like frequency, wavelength, and speed, can be studied using water waves in a ripple tank.

• Determining the wavelength of waves involves:
  • Utilizing a ruler to measure the screen's length.
  • Dividing this measured distance by the number of wavefronts.
• Calculating the frequency entails:
  • Timing the passage of a specific number of waves past a designated point.
  • Dividing the count of wavefronts by the recorded time.
• Finally, determining the wave speed is achieved by:
  • Applying the formula: wave speed = frequency × wavelength.

Features of a Wave

In explaining wave motion, it's crucial to understand various terms, including:

• Crest (Peak)
• Trough
• Amplitude
• Wavelength
• Frequency
• Wave speed
• Wavefront

Crest (Peak)

• A crest, or a peak, is the highest point on a wave above the equilibrium, or rest, position.
• For example, the topmost point of a water wave before it crashes onto the shore represents the crest.

Trough

• A trough is the lowest point on a wave below the equilibrium, or rest, position.
• Imagine the lowest point between two waves in an ocean; that is where the trough can be found.

Amplitude

• Amplitude is defined as:
  • The distance between the wave's undisturbed position and its peak or trough.
• Denoted by the symbol A and typically measured in meters (m).
• It represents the maximum or minimum displacement from the undisturbed position.

Wavelength

• Wavelength is defined as:
  • The distance between a point on a wave to the corresponding point on the subsequent wave.
• In a transverse wave, it can be measured from one peak to the next peak.
• In a longitudinal wave, it can be measured from the center of one compression to the center of the next.
• Represented by the symbol λ (lambda) and typically measured in meters (m).
• The distance along a wave is usually depicted on the x-axis of a wave diagram.

Frequency

• Frequency is the number of waves that pass a point in one second.
• It is represented by the symbol 'f' and is measured in Hertz (Hz).

Wave Speed

• Wave speed is the rate at which energy is transmitted through a medium.
• It is defined as the distance traveled by a wave per second.
• The symbol for wave speed is 'ν' and is measured in meters per second (m/s).
• Wave speed can be calculated using the formula: wave speed = frequency × wavelength.

Wavefronts

• Wavefronts provide a helpful way to visualize waves from above, with each wavefront representing a single wave.
• The illustration below demonstrates how wavefronts are depicted, with the arrow indicating the wave's direction, also known as a ray.
• The spacing between wavefronts corresponds to the wavelength: closer wavefronts indicate a shorter wavelength, while distant wavefronts signify a longer wavelength.