CCEA A-Level Physics 1210
Physical Quantities, Scalars and Vectors
Moments and Equilibrium
Linear Motion and Dynamics
Newton's Laws of Motion
Linear Momentum and Impulse
Work, Energy and Power
Current, Charge and Potential Difference
Resistance and Resistivity
Internal Resistance and Potential Dividers
Waves
Refraction
Lenses
Superposition, Interference and Diffraction
Quantum Physics
Wave-Particle Duality
Astronomy
Practical Skills and Data Analysis
Deformation of Solids
Thermal Physics
Uniform Circular Motion
Simple Harmonic Motion
The Nucleus and Radioactive Decay
Nuclear Energy, Fission and Fusion
Gravitational Fields
Electric Fields
Capacitors
Magnetic Fields
Charged Particles and Accelerators
Waves
The wave equation
- 3 things to know
- Unit AS 2
Overview
Wave equation and define each symbol, why the wave speed equals frequency multiplied by wavelength and speed of every electromagnetic wave in a vacuum.
What you need to know
Answer each one before you reveal it.
A note of frequency 256 Hz travels through air at 340 m s⁻¹. Calculate its wavelength.
A radio station broadcasts at 100 MHz. Calculate the wavelength of the transmission.
Questions from this subtopic
Each one with the model answer underneath.
- 1
State the wave equation and define each symbol.
Model answer
v = fλ, where v is the wave speed in m s⁻¹, f is the frequency in Hz and λ is the wavelength in metres.
- 2
Explain why the wave speed equals frequency multiplied by wavelength.
Model answer
In one period the wave advances exactly one wavelength, so v = λ/T, and since f = 1/T this becomes v = fλ.
- 3
A note of frequency 256 Hz travels through air at 340 m s⁻¹. Calculate its wavelength.
Model answer
λ = v/f = 340/256 = 1.33 m, and 256 Hz × 1.33 m returns 340 m s⁻¹ as given.
- 4
A radio station broadcasts at 100 MHz. Calculate the wavelength of the transmission.
Model answer
λ = c/f = 3.00 × 10⁸ / 1.00 × 10⁸ = 3.00 m, and 1.00 × 10⁸ Hz × 3.00 m returns 3.00 × 10⁸ m s⁻¹ as required.
- 5
Calculate the frequency of light of wavelength 600 nm in a vacuum.
Model answer
f = c/λ = 3.00 × 10⁸ / 6.00 × 10⁻⁷ = 5.00 × 10¹⁴ Hz, and 5.00 × 10¹⁴ Hz × 6.00 × 10⁻⁷ m returns 3.00 × 10⁸ m s⁻¹.
- 6
Water waves of frequency 2.0 Hz have a wavelength of 0.75 m. Calculate their speed.
Model answer
v = fλ = 2.0 × 0.75 = 1.5 m s⁻¹, and 1.5 m s⁻¹ ÷ 2.0 Hz returns the 0.75 m wavelength given.
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