Development, construction, and testing of a laboratory apparatus for determining interpole magnetic field, magnetic force and current using locally available materials

• Main Author: Daen, Eugenio P.
• Format: text
• Language: English
• Published: Animo Repository 1985
• Subjects: Physical instruments > Design and construction; Education; Physics
• Online Access: https://animorepository.dlsu.edu.ph/etd_masteral/1139
• Institution: De La Salle University

This study is focused on the development, construction and testing of an improvised current balance to demonstrate some principle in electromagnetism using locally available materials. The design is similar to the one suggested by Frank Tyler. The construction of the apparatus starts with the base board made of plywood and cut into the desired dimensions. Six holes are bored at specified points to accommodate four binding posts and two brass supports. A wooden spacer to hold the current frame of desired shape is pivoted at both ends. Attached to the spacer is a wooden balancer with a pointer at the free end. The free play of the pointer is limited by two pins supported at one end of the base board. The simple design of the apparatus can encourage teachers to duplicate it in their school shop. Assemblies A and B measure the interpole magnetic flux density of an electromagnet, and the current and magnetic force between parallel wires respectively. To test the null hypothesis that there is no significant difference in the performance between the improvised and commercial apparatus, the t-test between means for small independent samples was applied. Using 0.05 significant level, the t-test value obtained for activity 1 was 1.6 and 0.185 for activity 2. Both are below the critical value of 2.3 with 8 degrees of freedom. The null hypothesis is not rejected. The findings are summarized as follows: 1. The materials used for construction of the apparatus are plywood, brass rod, copper wire #14 and #16 A. Wg., binding post, screws, nails, paper clip, alligator clip and connecting wires. 2. The design of the apparatus is patterned from the suggested design by F. Tyler. Some parts are modified. 3. The parts are inexpensive and readily available at electrical stores in Raon St., Manila. 4. The total cost of the apparatus including labor cost as May 1985 is about P 300.00. This is around around 10 percent of the cost of commercial apparatus. 5. The apparatus can demonstrate basic principles in electromagnetism. 6. Both assembly of the apparatus (A and B) can obtain less than 10 percent of error. This is generally acceptable. 7. Except for the current frame, which can be easily deformed, the other components do not need careful handling. 8. There is no significant difference on the performance between the improvised and commercial apparatus. 9. Improvisation of apparatus economically help the school, thus minimize importation. 10. The apparatus is safe to operate since it uses low voltage D.C. Source. With this study, the researcher hopes that similar projects and innovations will be done. Locally made apparatus can be of best substitute for the commercial equipments.