Product Overview
This compact educational apparatus offers a modern alternative to the classic photoelectric effect experiment traditionally used to determine Planck’s Constant. Instead of using vacuum photo-tubes and monochromatic light sources, this method uses a series of LEDs—each with a known wavelength—to explore the fundamental relationship between photon energy and frequency.
When activated, each LED is adjusted to the precise voltage at which 2 microamps of current begins to flow. At this threshold, the LED is just beginning to conduct. The corresponding LED wavelength is labeled on the front panel and must be converted to frequency. Plotting frequency versus the “breakover” voltage (the voltage needed to reach 2μA) yields a straight line, the slope of which provides a calculated value for Planck’s Constant.
While this method is not as fundamental as using a traditional photoelectric tube, the cost is significantly lower, making it ideal for instructional settings where budget is key consideration.
This elegantly simple approach demonstrates the quantized nature of light energy, reinforcing that photon energy depends on frequency, not intensity—a core principle of quantum physics.
Key Features:
• Demonstrates the photoelectric effect using LEDs
• Breakover voltage is recorded at 2μA threshold current
• LED wavelengths labeled for frequency conversion
• Supports data plotting to derive Planck’s Constant
• Safe, low-voltage, classroom-friendly operation
Physical Specifications:
Dimensions: 120 × 100 × 60 mm; 4.7 × 3.9 × 2.4 in
Weight: 0.15 kg; 0.33 lb
Designed and manufactured in Australia.
