Global Journal of Science Frontier Research, A: Physics and Space Science, Volume 22 Issue 1

The number of turns was not altered because a greater number of turns results in a greater force of the electromagnet. On the other hand, it was ensured that the cable was tightly wound around the core, to avoid the formation of air gaps and that this caused the dispersion of the magnetic flux, as explained in section 2.3.2. Iron electromagnets, having better magnetic properties, produce stronger magnetic fields, while steel electromagnets generate weaker fields. For this reason, if in the different attempts the type of material of the nuclei had been changed, the variation of the magnetic field could have altered the pattern of the results obtained. Cables with different gauges will have different resistances, since resistance is indirectly proportional to cross- sectional area. ii. Types of variables Table 2: Identification and analysis of dependent and independent variables Dependent variable Independent variable • Voltage value for which the electromagnet can no longer support the weight of the nut. This result depends on the temperature to which the winding is heated, since the higher the temperature, the lower the current through the wire. When the minimum current necessary to maintain a perceptible electromagnetic effect is reached, that is, before the nut is dropped, the minimum voltage will also be reached due to the direct proportionality between these two variables. The voltage was measured by first raising it to a fixed amount of 6V, chosen on the basis of the ease of joining the nut to the electromagnet. Then, the voltage was slowly reduced until the nut falled off. It is important to note that great care was taken to lower the voltage in constant intervals because an analogue power supply is used which, unlike digital circuits, is more sensitive to user movement. Consequently, if the source fails to supply the required value of voltage, the nut is no longer attracted by the electromagnet. • Wire coil temperature Twenty-two measurements of different temperatures were made because of the considerable variability of each individual measurement. This is due, in turn, to the fact that the experimental procedure has to be done quickly to avoid cooling the coil. Likewise, it is difficult to pinpoint the exact moment when the nut falls. On the other hand, the intervals between the temperature increases cannot be accurately controlled for the reasons mentioned above. However, the experiment tried to obtain measurements for each interval of 10 K, starting with approximately 293.15 K and ending with temperatures close to 333.15 K. Having several measurements of the same phenomenon allows greater confidence in the calculation of an accurate mean measurement. • Holding force of the electromagnet This variable is temperature-dependent for the reasons mentioned previously. b) Methods and tools This section details the qualities of the instruments, tools and materials used in the experiment, in addition to indicating the steps carried out in each of the procedures. Relationship between Temperature and the Holding Force of an Electromagnet in a Changing Magnetic Field 1 Year 2022 15 © 2022 Global Journals Global Journal of Science Frontier Research Volume XXII Issue ersion I VI ( A )