In this paper, a simple analysis yet a straight forward method of determining the Planck’s constant by
evaluating the stopping potential of five different colors of light emitting diodes (LEDs) is presented.
The study aimed to identify the Planck’s constant based on the relationship between the potential
difference of LEDs to their respective frequencies under room temperature with low illumination of
ambient light by applying a simple theoretical analysis. The experiment was performed by connecting
the circuit in series connection and the voltage reading of LEDs were recorded and then presented in a
graph of frequency, f versus stopping voltage, Vo. To determine the Planck’s constant, the best fit line
was analyzed and the centroid was also identified in order to find the minimum and maximum errors
due the gradient of the graph. From the analysis, results showed that the Planck constant value was
(5.997 ± 1.520) × 10–34 J.s with approximately 10% of deviation from the actual value. This
demonstrates that a simple analysis can be utilized to determine the Planck’s constant for the purpose
of the laboratory teaching and learning at the undergraduate level and can be served as a starting point
for the students to understand the concept of quantization of energy in Modern Physics more
effectively. This is to further suggest that the Planck’s constant can be identified via a low-cost and
unsophisticated experimental setup.