Understanding Waves in GCSE Physics

What are Waves?

In physics, a wave is a disturbance that transfers energy through a medium, without causing any permanent displacement of particles. Waves can be classified into two main types:

Transverse Waves

In transverse waves, the particles of the medium vibrate perpendicularly to the direction of wave propagation. Examples include:

• Light waves
• Waves on a string
• Electromagnetic waves (radio, microwave, infrared, UV, X-rays, gamma rays)

Longitudinal Waves

In longitudinal waves, the particles of the medium vibrate parallel to the direction of wave propagation. Examples include:

• Sound waves
• Seismic P-waves

Wave Properties

All waves share common properties:

• Amplitude: The maximum displacement of a particle from its rest position
• Wavelength: The distance between two consecutive crests or troughs
• Frequency: The number of wave cycles that pass a given point per unit time
• Period: The time taken for one complete wave cycle
• Wave Speed: The speed at which the wave travels through the medium

The Electromagnetic Spectrum

The electromagnetic spectrum is the range of all possible frequencies of electromagnetic radiation. It includes:

• Radio waves (used for radio and television broadcasting)
• Microwaves (used in microwave ovens and telecommunications)
• Infrared waves (felt as heat radiation)
• Visible light (the only part of the spectrum we can see)
• Ultraviolet waves (causes sunburn and is used in disinfecting)
• X-rays (used in medical imaging and security screening)
• Gamma rays (used in cancer treatment and produced in nuclear reactions)

Sound Waves

Sound waves are longitudinal waves that require a medium to travel through. They have various applications:

• Ultrasound: High-frequency sound waves used in medical imaging and industrial processes
• Echo Sounding: Using reflected sound waves to determine the depth of water bodies
• Seismic Waves: Waves generated by earthquakes, including primary (P) and secondary (S) waves

Worked Example: Calculating Wave Properties

Question: A wave has a frequency of 5 Hz and a wavelength of 2 m. Calculate the wave speed.

Given: Frequency (f) = 5 Hz, Wavelength (λ) = 2 m

Solution:

1. The wave speed (v) is related to frequency and wavelength by the equation: v = f × λ
2. Substituting the given values: v = 5 × 2 = 10 m/s

Answer: The wave speed is 10 m/s.

Further resources:

• BBC Bitesize: Waves
• TRH Learning: Physics Blog