Spektra: Jurnal Fisika dan Aplikasinya

Front Matter SPEKTRA Volume 9 Issue 2, August 2024

Editor Spektra — 2024-08-30

Back Matter SPEKTRA Volume 9 Issue 2, August 2024

Editor Spektra — 2024-08-30

Thickness Measurement and Sensitivity of Copper/Nickel Electroplating Results of Electrolyte Solution Temperature Variation

Rizka Nuzul Islamiyati — 2024-08-12

Currently, cryogenic thermometers are needed and one of the uses of cryogenic thermometers is to measure the temperature of food preservation flasks. Research has been conducted on the manufacture of cryogenic thermometers derived from Cu/Ni coils by electroplating process with temperature variation treatment of electrolyte solution. The purpose of this study is to determine the effect of electrolyte solution temperature variation treatment on Ni thickness and Cu/Ni sensitivity as a low-temperature sensor. Electroplating was carried out with electrolyte temperature parameters of 30˚C-70˚C, electrode distance of 4 cm, voltage of 4.5 volts, and coating time of 4 minutes. The electrolyte solution was a mixture of NiSO₄ 260 g, NiCl₂ 60 g, H₃BO₃ 40 g, and Aquades 1000 mL. Based on the results of the study, a remarkable condition was obtained on the thickness of Ni; namely, at 40 ˚C, the thickness increased to 1.08 mm. In addition, the best temperature can produce the greatest sensitivity value in Cu/Ni coil electroplating, namely at 50 ˚C.

Exploring Weak Gravitational Lensing Effects by a Regular Black Hole

A. K. Durrani — 2024-07-15

Gravitational lensing is one of the physical consequences of Einstein’s general theory of relativity, which has been observationally confirmed. This work aims to study the weak gravitational lensing scenario where the lens is a spherically symmetric, charged-nonsingular black hole that asymptotically behaves as the Reissner-Nordström (RN). The difference exists in the higher-order expansion. Therefore, the metric function of the regular charged black hole is expanded up to the fourth order, and the deflection angle is calculated. The thin lens equation is used, leading to five images: two imaginary and three real images. The exact positions of the images and magnification properties are calculated by providing the physical parameters such as mass, charge, and distances. Our calculation shows that the third image position shifted away from the optical axis. The formalism is applied to the case of a supermassive black hole located at the center of our galaxy with the assumption that it has an electric charge.

Enhanced Approaches to Gravitational Lensing: A Regular Charged Black Hole in Weak Field Limit

H. M. U. Din — 2024-07-22

Gravitational lensing, an integral aspect of general relativity, profoundly impacts our understanding of black holes (BH’s). The presence of a centered singularity resulting from gravitational collapse is a fundamental characteristic of a BH. Nonetheless, the exploitation of non-linear electrodynamics (NLED) divulges the emphatic concept of non-singularity. Our analysis primarily focuses on calculating the deflection angle in the weak field approximation, deliberately excluding the original spacetime configuration. The photon’s effective geometry is typically linked to NLED. Instead, a photon traverses an effective null geodesic that aligns with the geometry of a regular metric. The findings reveal an additional term in the deflection angle compared to the Reissner-Nordström (RN) metric, evidenced by a shifted positional displacement of the tertiary image associated with a regular BH. This study succinctly encapsulates these findings, positioning them within the extensive terminology ambient to BH’s singularity and GL, thus edifying the scientific memoir with precise astrophysical insights.

Synthesis Process and Nutritional Evaluation of Plantain as a Supplementary Food for Toddlers in Sierra Leone: A Study Utilizing Biuret’s, Benedict’s, and Iodine Solution Test

L. Koroma — 2024-09-06

Research on developing plantain fruit into juice, jam, ice cream, and fritters as a food supplement for toddlers was conducted in Sierra Leone. The work was done at the Mosoudo section of Daru village, Jawie Chiefdom, in Kailahun District. Four bunches of plantains were harvested from Jawei Chiefdom and stored in Mosoudo. Two bundles of the raw plantain were peeled, dried, and ground into powder, while the other two left to ripen at room temperature for nine days. Test were conducted using Iodine solution, Benedict solution, and Biuret test to check the presence of starch, glucose, and protein, respectively, in both the powdered and ripe plantain. The ripe plantains were then made into juice, jam, ice cream, and fritters. Fifty mothers/caregivers, along with their children, were randomly selected to evaluate the color, taste, smell, and texture of the four plantain products. The sensory evaluation results showed high acceptance levels: color (53.5%), taste (59.0%), smell (61%) and texture (59.9%). The results suggest that the project could successfully provide nutritious and appealing food supplements for toddlers in Sierra Leone. It was recommended that the government and NGOs promote the cultivation of plantains instead of importing food supplements for children in Sierra Leone.

Gravitational Lensing for A Spherically Symmetric Regular Charged Black Hole in Weak Field Limit

M. F. Shidik — 2024-09-06

Gravitational lensing is an integral part of the study of general relativity, as it is one of the direct consequences of general relativity. The existence of singularity within the black hole due to gravitational collapse is one of the key properties of the black hole. However, the introduction of non-linear electrodynamics (NLED) offers an intriguing possibility: nonsingular black holes. This work focuses on calculating the deflection angle within the weak field limit. Here, the photon's effective geometry associated with NLED is not incorporated; instead, the regular metric is utilized as it is, without presupposing its origins in NLED. A correction term in the deflection angle to the Reissner-Nordstrom (RN) case was found. This term manifests as a displacement in the position of the third image associated with the black hole.