Features of a wave, how to determine wave speed, naming a transverse wave, using data to identify the type of radiation emitted

🌊 1. Features of a Wave

Key Parts of a Wave

Feature

Description

Wavelength (λ)

Distance between two similar points (e.g., crest to crest)

Crest

Top of the wave

Trough

Bottom of the wave

Amplitude

Maximum displacement from rest position

Frequency (f)

Number of waves passing a point per second (Hz)

Period (T)

Time for one complete wave (s)

Wave speed (v)

How fast the wave moves (m/s)

Key Concept

  • Waves transfer energy, not matter

⚡ 2. How to Determine Wave Speed

Formula

v=f×λv = f \times \lambdav=f×λ

  • vvv = wave speed (m/s)

  • fff = frequency (Hz)

  • λ\lambdaλ = wavelength (m)

Example

  • f = 50 Hz, λ = 2 m

v=50×2=100 m/sv = 50 \times 2 = 100\, \text{m/s}v=50×2=100m/s

Practical Method

  • Measure distance travelled by a wave over time → speed = distance ÷ time

🎸 3. Naming a Transverse Wave

  • In a transverse wave, particles move perpendicular to the direction of energy transfer

Examples:

  • Light waves

  • Electromagnetic waves

  • Water waves

  • Seismic S-waves

Key Tip

  • All EM waves are transverse

☢ 4. Using Data to Identify the Type of Radiation Emitted

Step 1: Identify Key Properties

  • Frequency (f), wavelength (λ), energy (E)

Step 2: Use EM Spectrum

Radiation

Wavelength

Energy

Example

Radio

> 1 m

Low

Communication

Microwaves

10⁻² m

Low

Cooking

Infrared

10⁻⁵ m

Low-medium

Heaters

Visible

4 × 10⁻⁷ – 7 × 10⁻⁷ m

Medium

Light

Ultraviolet

10⁻⁸ m

High

Sterilisation

X-rays

10⁻¹¹ – 10⁻⁹ m

Very high

Medical imaging

Gamma rays

< 10⁻¹² m

Extremely high

Cancer treatment

Step 3: Compare Data

  • Example: A wave with λ = 500 nm → visible light

🔗 Big Links

  • Wavelength, frequency, and wave speed are directly related

  • Transverse waves → perpendicular motion

  • EM spectrum properties allow identification from data

⭐ Exam Tips

  • Always label crest, trough, wavelength, amplitude

  • Use v = f × λ for speed calculations

  • Know examples of transverse waves

  • Use wavelength/frequency data to identify EM radiation