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Putut Marwoto
Universitas Negeri Semarang, Semarang
Biochemistry, Genetics & Molecular Biology Chemistry Education Mathematics Physics

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A Simple Photovoltaic Experiment for Measuring Planck’s Constant Using Colour Lasers Nuri Nuri; Putut Marwoto; Sunyoto Eko Nugroho; Agus Yulianto; Bambang Subali; Sulhadi Sulhadi; Sumarli Sumarli
Variabel Vol 8, No 2 (2025): OCTOBER 2025
Publisher : STKIP Singkawang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.26737/var.v8i2.8664

Abstract

The photovoltaic experiment provided a simple, affordable method to determine Planck’s constant through empirical learning. This experiment allowed students to present concrete data using easily available, low-cost materials. The experiment utilised a photovoltaic method, employing a simple, self-designed setup that used three laser pointers with wavelengths of 650nm (red), 535nm (green), and 405nm (blue) as independent variables. A 6V, 1W mini solar cell was used as the target, while the speed of light and electron charge were treated as control variables. The laser pointers were powered by a 3V battery. The data were analysed by plotting the relationship between 1/λ (inverse wavelength) and the measured voltage as the dependent variable. A linear regression analysis was performed to obtain the gradient, which was used to calculate Planck’s constant. The experiment yielded a calculated Planck’s constant of 7.09×10-35Js, with a deviation of 5.69 x 10-34Js, resulting in a relative error of 8.89%. This relative error could be attributed to several factors, including refraction effects caused by the glass layer and adhesive used to protect the semiconductor plate of the solar cell, as well as discrepancies between the actual wavelengths of the laser beams and the labelled wavelengths on the laser pointers.
Examining the Absorbency and Elasticity Properties of Modified Coconut Fibre: An Alternative Material for Diapers Filling Intan Kusumawati; Putut Marwoto; Ani Rusilowati; Woro Sumarni; Sigit Priatmoko
Variabel Vol 8, No 1 (2025): APRIL 2025
Publisher : STKIP Singkawang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.26737/var.v8i1.6193

Abstract

Research on absorbent core and elastic-modified coconut fibre is motivated by the use of coconut fibre in terms of water absorption and elasticity. This study aims to: (1) determine the percentage of the absorbent core and elastic-modified coconut coir; (2) compare the percentage of the absorbent core and elastic-modified coconut fibre to the diapers X. The design used was experimental. The tools and materials consisted of modified coconut fibre, a Pasteur pipette, a specimen clamp, and a software system. Modified coconut coir was made from a mixture of Cinnamomum verum and Mutingia calabura L., with a sample mass ratio to diapers X, which was 1:40, circular shape with a diameter of 3 cm. The treatments for modified coconut coir were sun drying (Sample A) and a hair dryer (Sample B), which resulted in differences in the Absorbent core (Ab) and Elastic (E). The sample was forwarded for the E-test through the Tracker software system, which can detect the centre of mass of the object through the experimental video recording, and the other sample was measured Ab through the difference in the volume of water absorption. The results showed that Sample B could be used as an engineering material for Ab and E diapers X. It was concluded that: (1) %Ab-Sample B = 38.36%, %Ab-Sample A = 25.57%, %E-Sample B = 1.2%, %E-Sample A = 0.5%; (2) comparison of %E-Sample B to %E-Diapers X was 67%, and %E-Sample A to %E-Diapers X was 27%.
Co-Authors Agus Yulianto Ani Rusilowati Bambang Subali Intan Kusumawati Nuri Nuri Sigit Priatmoko Sulhadi Sulhadi Sumarli Sumarli Sunyoto Eko Nugroho Woro Sumarni