Determining Planck's Constant Using LED
Measure threshold voltages of different colored LEDs to calculate Planck's constant
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Controls
Experiment Setup
Voltage
0.00 V
Current
0.00 mA
Data Collection
| Color | λ (nm) | ν (Hz) | V (V) |
|---|
Voltage vs. Frequency Graph
Threshold Voltage (V)
Frequency (×10¹⁴ Hz)
Theory
The energy (E) of photons emitted by an LED is related to the threshold voltage (V) by:
E = eV = hν
Where:
- e = electron charge (1.602 × 10⁻¹⁹ C)
- V = threshold voltage
- h = Planck's constant
- ν = frequency of light
By measuring V for different ν and plotting V vs. ν, the slope gives h/e.