Speed of Light Calculator
Calculate light travel distance, time, wavelength, and frequency with electromagnetic wave analysis
Speed of Light and Electromagnetic Wave Calculator
Light speed varies in different media due to refractive index
Time duration for light to travel
Unit for displaying light speed
Speed of Light Results
Fundamental Physics
c = 299,792,458 m/s
Speed of light in vacuum (exact)
v = c / n
Speed in medium
d = v × t
Distance formula
λ = c / f
Wavelength-frequency relation
Light Travel Times
To Moon: 1.28 s
To Sun: 8.32 min
To Mars: 12.51 min
To Proxima Centauri: 4.24 years
Quick Examples
Example Calculations
Light Travel Distance
Problem: How far does light travel in 100 seconds in vacuum?
Given: c = 299,792,458 m/s, t = 100 s
Formula: d = c × t
Calculation: d = 299,792,458 × 100 = 29,979,245,800 m
Result: Light travels ~30 billion meters (30,000 km)
Electromagnetic Spectrum
Red Light: λ ≈ 700 nm, f ≈ 430 THz
Green Light: λ ≈ 550 nm, f ≈ 545 THz
Blue Light: λ ≈ 450 nm, f ≈ 667 THz
X-rays: λ ≈ 1 nm, f ≈ 300 EHz
Speed Comparisons
Electromagnetic Spectrum
Radio Waves
λ > 1 m, f < 300 MHz
Microwaves
1 mm - 1 m, 300 MHz - 300 GHz
Infrared
700 nm - 1 mm, 300 GHz - 430 THz
Visible Light
380-700 nm, 430-790 THz
Ultraviolet
10-380 nm, 790 THz - 30 PHz
X-rays
0.01-10 nm, 30 PHz - 30 EHz
Gamma Rays
λ < 0.01 nm, f > 30 EHz
Understanding the Speed of Light
Fundamental Constants
The speed of light in vacuum (c) is exactly 299,792,458 meters per second. This is a fundamental physical constant that represents the maximum speed at which all matter, energy, and information in the universe can travel.
Key Properties
- •Universal Speed Limit: Nothing can travel faster than c
- •Medium Dependent: Light slows down in materials
- •Electromagnetic Waves: All EM radiation travels at c in vacuum
- •Invariant: Same for all observers (special relativity)
Mathematical Relationships
c = λ × f
v = c / n
E = h × f
Refractive Index
The refractive index (n) determines how much light slows down in a material:
n = c / v
Where v is the speed of light in the material. Higher refractive index means slower light speed and more bending at interfaces.
Historical Measurements
Early Attempts
- • Galileo (1638): Attempted with lanterns
- • Rømer (1676): Jupiter's moons - first estimate
- • Bradley (1728): Stellar aberration method
Modern Methods
- • Fizeau (1849): Rotating gear wheel
- • Michelson (1926): Rotating mirror method
- • Laser interferometry (1970s): Precise measurements
Modern Applications
GPS Technology
Satellite positioning requires precise timing based on light speed
Fiber Optics
Internet communications depend on light speed in optical fibers
Astronomy
Distance measurements using light travel time