Wavelength
Physical length of one wave cycle for a given frequency.
Formula
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Example
f=2.4 GHz: λ = 3×10⁸/2.4×10⁹ = 0.125 m
How it works
This formula links how fast a wave travels to how often it repeats. Since speed equals distance travelled per second, a wave’s wavelength is the distance covered in one cycle, so dividing the wave speed by the frequency gives the length of one wave. For electromagnetic waves in free space, the speed is the speed of light, so higher-frequency waves have shorter wavelengths.
When to use it
Use this when converting between frequency and wavelength for radio, Wi‑Fi, mobile networks, or other electromagnetic waves. It is also useful when comparing bands or checking whether an antenna size matches the signal wavelength.
Worked example, step by step
Suppose a signal has frequency f = 900 MHz. Convert to hertz: f = 900 × 10^6 Hz Use the formula: λ = c / f Substitute values: λ = (3 × 10^8 m/s) / (900 × 10^6 Hz) Calculate: λ = 0.333... m Final answer: λ ≈ 0.33 m
Common mistakes to avoid
- Using MHz or GHz in the formula without converting them to Hz first
- Forgetting that c is only the speed of light for electromagnetic waves in free space
- Reversing the formula and multiplying c by f instead of dividing c by f
Did You Know?
A Wi-Fi antenna is often a quarter wavelength — about 3 cm at 2.4 GHz.
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