Planck's Constant Apparatus

Item #P2-7135

$185.00 Bundle Discount

Unit Price	$185.00
6+	$172.00

Determine Planck’s constant using LED thresholds

Make one of modern physics’ toughest ideas measurable with a compact, pre-constructed setup that students can run successfully in a single lab period. The Planck’s Constant Apparatus uses a series of LEDs from deep blue to infrared. Students record the voltage at which each LED just begins to emit light, then graph energy vs. frequency to determine an experimental value of Planck’s constant—linking quantum theory to real data.

Why Teachers Love the Planck’s Constant Apparatus

Cost-effective, classroom-ready take on a hard topic: Pre-built and durable so you can investigate Planck’s constant without a complicated electronics build.
Designed for clean measurements: Built-in voltage control, monitoring points for current/voltage, and a protection resistor to safeguard LEDs.
Improves precision for students: The included viewing tube helps students identify the LED turn-on threshold more consistently.

What You Can Teach with the Planck’s Constant Apparatus

Ideal for high school AP/IB and introductory college modern physics:

Planck’s constant and quantization: Determine (h) experimentally from LED threshold data.
Photon energy–frequency relationship: Verify (E = hf) using visible and IR LEDs.
Semiconductors & band gap energy: Connect color (frequency) to LED band gaps and required electrical energy.
Graphing & linear modeling in modern physics: Build a best-fit line to extract a fundamental constant from slope.

How It Works

A series of LEDs span colors from deep blue to infrared.
Students slowly raise the voltage for each LED and note the point where it just begins to glow.
Plotting the electrical energy input versus the LED’s light frequency produces a straight-line graph, and the slope gives an experimental value for Planck’s constant.