Planck’s Constant & Photoelectric Effect Experiment Apparatus – Complete Physics Lab System (SS20802)

Planck’s Constant & Photoelectric Effect Apparatus (SS20802)

The SS20802 Planck’s Constant Measuring Instrument is a complete modern physics laboratory system designed to demonstrate the photoelectric effect and experimentally determine Planck’s constant.

Using a vacuum phototube and precision voltage control, students measure the stopping potential of emitted electrons at multiple wavelengths of visible light. By plotting electron kinetic energy versus frequency, students directly calculate Planck’s constant and determine the work function of the metal.

This apparatus provides a powerful hands-on demonstration of the quantum nature of light and Einstein’s explanation of the photoelectric effect.

Key Learning Outcomes

Students will:

• Observe the photoelectric effect in real time

• Measure photocurrent as a function of light intensity

• Determine stopping potential

• Calculate electron kinetic energy

• Plot KE vs frequency

• Experimentally derive Planck’s constant

• Determine the work function of a metal

Bring Quantum Physics Out of the Textbook

The SS20802 transforms Einstein’s photoelectric equation from theory into measurable data. Students directly verify:

hf − W = KE

A foundational experiment in quantum mechanics — made tangible, measurable, and teachable.

Technical Features

• Vacuum phototube detector

• 12V / 35W halogen tungsten light source

• Five precision wavelength filters (460–635 nm)

• Adjustable accelerating voltage

• Voltage polarity switch

• Digital voltage and photocurrent display

• Current multiplier for high sensitivity measurements

• Adjustable light distance rail with scale

• Dark-box housing for stray light reduction

Accuracy & Performance

• Dark current < 0.003 µA

• Accelerating voltage error < ±2%

• Experimental value of Planck’s constant within ±15% of accepted value

Included

• Instrument base unit

• Five color filters

• Light source assembly

• Dark-box housing

• User manual

• Student lab activity guide