Hair Diffraction Calculator
Measure hair width using laser diffraction patterns and wave interference
Calculate Hair Width from Diffraction
Distance from hair to the projection surface
Which dark spot to measure for better accuracy
Check laser pointer label (common: 532nm green, 650nm red)
Distance from center bright spot to selected dark spot
Hair Width Results
Formula used: w = n × λ × x / D
Laser color: Green (532 nm)
Diffraction angle: 0.000°
Measurement precision: 100.0% relative to 1st dark spot
Hair Width Analysis
Example Experiment
Typical Hair Measurement
Setup: Green laser pointer (532 nm)
Distance to wall: 2.0 meters
Distance to 1st dark spot: 2.1 cm
Hair type: Human head hair
Calculation
w = 1 × 532×10⁻⁹ × 0.021 / 2.0
w = 1.117×10⁻⁸ / 2.0
w = 55.9 μm
Experiment Setup
Mount Hair
Tape a single hair vertically
Use clear tape to hold hair straight
Shine Laser
Point laser perpendicular to hair
Keep steady distance from wall
Measure Pattern
Mark center and dark spots
Use ruler for precise measurements
Common Laser Wavelengths
Measurement Tips
Use a single, straight hair strand
Keep laser perpendicular to hair
Measure multiple times for accuracy
Use higher-order dark spots for precision
Never look directly into laser
Understanding Hair Diffraction
What is Hair Diffraction?
Hair diffraction occurs when laser light passes around a thin hair strand, creating an interference pattern of bright and dark spots. This phenomenon demonstrates the wave nature of light and allows precise measurement of microscopic objects.
The Physics Behind It
- •Light waves bend around the hair (Huygens' principle)
- •Waves from hair edges interfere with each other
- •Constructive interference creates bright spots
- •Destructive interference creates dark spots
Diffraction Formula
w = n × λ × x / D
- w: Width of the hair (meters)
- n: Order of dark spot (1, 2, 3, ...)
- λ: Wavelength of laser light (meters)
- x: Distance from center to dark spot (meters)
- D: Distance from hair to screen (meters)
Note: This is a simplified formula valid for small angles (x ≪ D)
Historical Context
This experiment is based on the famous Young's double-slit experiment from 1801, which proved that light behaves as a wave. Thomas Young's work settled a centuries-long debate between particle and wave theories of light, though quantum mechanics later showed light has both properties.
Applications
Scientific Applications
- • Microscopic measurements
- • Quality control in manufacturing
- • Fiber optics research
- • Optical instrument calibration
Educational Value
- • Demonstrates wave-particle duality
- • Shows interference patterns
- • Practical physics application
- • Accessible home experiment