Wave Speed Calculations
IGCSE Edexcel Physics
3.5-3.7 Wave Speed Relations
Key Concepts:
Use $v = f\lambda$ for all waves. Sound and EM waves follow the same relationship.
Section A: Calculations
1. A sound wave has frequency 250 Hz and speed $340\,m/s$. Calculate wavelength.
[2]
2. An EM wave has wavelength 0.5 m. Calculate frequency if speed is $3.0 \times 10^8\,m/s$.
[3]
3. A wave has frequency 8 Hz and wavelength 1.2 m. Calculate speed.
[2]
Total marks: 7
Mark Scheme
1.
$\lambda = v/f = 340/250 = 1.36\,m$ [2]
2.
$f = v/\lambda = (3.0 \times 10^8)/0.5 = 6.0 \times 10^8\,Hz$ [3]
3.
$v = f\lambda = 8 \times 1.2 = 9.6\,m/s$ [2]