V-I curves of different light frequencies
(Click figure to enlarge)
Cutoff voltage vs light frequency
(Click figure to enlarge)
User interface panel of software
(Click photo to enlarge)
Features
Manual or auto measurement modes
Integrated structure and easy to operate
No crosstalk between spectral lines
Built-in data acquisition card with software for PC use via USB port
Introduction
The LEAI-52 Apparatus is an advanced version of the Planck's constant determination system designed to provide high-accuracy results in demonstrating the photoelectric effect. This apparatus allows for precise measurements of the characteristic curve of a photoelectric tube, the verification of the "red limit" frequency, and the calculation of Planck's constant using Einstein's photoelectric equation. With a precision photoelectric tube, the apparatus enables measurements with an accuracy of 3%.
Students can conduct experiments either by manually recording data or by using the built-in data acquisition card for automatic data transfer to a PC via a USB port. The acquired data can be processed using accompanying software for further analysis. This model offers a higher level of accuracy and advanced features compared to the basic model, making it ideal for advanced physics education.
Using the LEAI-52, students can perform a range of experiments and achieve the following learning objectives:
1. Demonstrate the Photoelectric Effect:
Students can observe and analyze the photoelectric effect, where light striking a metal surface releases photoelectrons. The experiment demonstrates the quantum nature of light and supports the theory that light has particle-like properties.
2. Measure the Characteristic Curve of a Photoelectric Tube:
Students can study the I-V characteristic curve of a photoelectric tube, which shows the relationship between the photoelectron current and the applied voltage. This curve provides insight into the behavior of photoelectrons under varying conditions.
3. Verify the Existence of "Red Limit" Frequency:
The experiment enables students to verify the existence of the "red limit" frequency (the minimum frequency of light required to emit photoelectrons). This observation aligns with Einstein's equation and provides strong evidence for the quantization of energy in light.
4. Determine Planck’s Constant:
By applying Einstein's equation for the photoelectric effect, students can determine Planck's constant with a high degree of accuracy. The data acquired from the experiment is used to calculate this fundamental constant, which is central to the understanding of quantum mechanics.
5. Use of Data Acquisition and Analysis Software:
Students can enhance their understanding of data analysis techniques by using the built-in DAQ and related software to process the data automatically acquired by the system. This provides a more efficient and accurate way to analyze experimental results.
The instruction manual contains comprehensive materials including experimental configurations, principles and step-by-step instructions. Please click Experiment Theory and Contents to find more information about this apparatus.
Specifications
| Description | Specifications |
| Wavelength of filters | 365 nm, 405 nm, 436 nm, 546 nm, 577 nm |
| Size of apertures | 2 mm, 4 mm, 8 mm, 10 mm, 12 mm |
| Light source | 50 W Mercury lamp |
Photocell | Wavelength range: 340 ~ 700 nm |
| Cathode sensitivity: ≥1 µA (-2 V ≤ UKA ≤ 0 V) | |
| Anode dark current: ≤5×10-12 A (-2 V ≤ UKA ≤ 0 V) | |
| Current range | 10-7 ~ 10-13 A, 3-1/2 digit display |
| Voltage range | I: -2 ~ +2 V; II: -2 ~ +20 V, 3-1/2 digit display, stability ≤0.1 % |
| Zero drift | < ±0.2% of full scale (for scale 10-13 A) within 30 minutes after warm-up |
| Measurement method | Zero current method and compensation method |
| Measurement error | 3% |
Parts List
| Description | Qty |
| Main Unit | 1 |
| Electric Control Unit | 1 |
| Special BNC Cable | 2 |
| USB Cable | 1 |
| Software CD | 1 |
| Power Cord | 1 |
| Instructional Manual | 1 |
V-I curves of different light frequencies
(Click figure to enlarge)
Cutoff voltage vs light frequency
(Click figure to enlarge)
User interface panel of software
(Click photo to enlarge)
