Physics Lab Report 70615r

Magnetic Field and Magnetic Induction Michael Mabini, Christ Joseph P. Rallos, Klein S. Tayo STEM Track – Senior High School Department, University of San Carlos, Cebu City [email protected] Abstract This study presents a student lab experiment focusing on Magnetic Field and Magnetic Induction to measure voltage generated by the movement of magnet through a coil and investigate how speed, reversing magnet, and magnets of different strength affect the induced voltage; determine the magnetic field at varying points surrounding a bar magnet; and to confirm the existence and establish the characteristics of the current generated by the motion of the magnet. The students carried out the study through the use of magnet, coil and magnetic probe. The concept of Electromagnetic Induction summarized in Faraday’s Law allowed the students to come up with the study.

I. Introduction Michael Faraday’s discovery of producing electrical current in circuits through the use of force produced by magnetic field has been used to operate electrical devices commonly used today. This discovery shows the relationship between electricity and magnets which was later on called as Faraday’s Law of Electrical Induction. The generation of electrical voltage is done through the movement either by magnet in and out of a coil or vice versa. The motion allows the simultaneous production of magnetic flux and electromotive force. The faster the speed of the movement, the greater magnetic flux and electromotive force there are. Two essential materials that enable the production of electromotive force are magnet and coil. Through the manipulation of these two materials, the entire idea of this study can be proven true. Therefore, the investigation of a permanent magnet’s magnetic field strength as well as a current-carrying coil is the main objective of this study. Theory: Faraday and Henry both discovered that a potential difference could be produced across the ends of a wire by moving a magnet in or out of a coil. This is called electromagnetic induction. This phenomenon is summarized by Faraday’s Law which states that the induced voltage in a coil is proportional to the product of the number of turns in the coil and the rate at which the magnetic flux changes within the coil.

II. Methodology Part A. Magnetic Induction The coil of wire was connected to the yellow and black sockets of channel 3 of coach lab II (the yellow socket was for the signal and the black socket was the ground. To be able to measure positive and negative voltage signals, the voltmeter that has to be used in the coach lab 6 program must be CMA -10V to + 10V). The “voltmeter icon” was right clicked and “display as a meter” was chosen, then upper right empty pane was clicked to display as meter. The voltmeter icon was right clicked again then the display as diagram was used then the lower right empty pane was clicked to display a diagram, the diagram was right clicked again and the diagram setting was adjusted to minimum of -1.5V and maximum of 1.5V and the measurement of frequency was adjusted to 30/sec and so as the measurement of Frequency: 2 and Time: 10 The magnet was inserted at the center of the coil, and the magnet remained at rest at the center and along the axis of the coil and the start button was clicked to see measurements. Next, the magnet was placed 5 cm away from the edge of the coil and let it stayed at rest in its position and the start button was clicked to measure. The magnet was slowly moved going in and out of the coil and the length of the magnet parallel to the axis of the coil and the start button was clicked to see measurements. Lastly, the magnet was moved fastly going in and out of the coil while keeping the length of the magnet parallel to the axis of the coil and the start button was clicked to see measurements. As we finish each procedure, we recorded each data for analysis. Part B. Measurement of Magnetic Field at different points around a Bar Magnet The magnetic field of a permanent magnet was measured through the use of magnetic probe. A permanent magnet was placed on a space provided in our lab journal. In the lower left of the coach 6 window, the “magnetic field sensor icon” was dragged to channel 1 of Coachlab II . Next, the “magnetic Field sensor icon” was right clicked and the “display a meter” was chosen. The same procedure was done to display a table to the lower right empty plane. Then, the magnetic probe was placed at point A in the illustration in the worksheet. The magnetic probe was positioned perpendicular to the magnetic field lines and the meter reading of the magnetic field was observed. The start button was clicked and the measurements were observed. Afterwards, on our worksheet, the reading that has the maximum value was recorded and we repeated the steps for points B, C, D and E. Part C. Measurement of Magnetic Field of an Electromagnet ( a current-carrying coil ) Similar procedures in part B was obtained in the magnetic field at these points, but the permanent magnet in part B was not used in this part of the experiment. The power supply was switched on and 2.5V was set, then the power supply was switched off. Next, the coil of wire was connected to the power supply, then the power supply was switched on. The current that was

indicated in the power supply was recorded in the worksheet. The tip of the magnetic probe was placed at the center of the coil using the same coach 6 setting that was used in part B, then the start button was clicked to start the measurement. The maximum reading of the magnetic probe was used as the values for recording, the signs (+ or -) was also included in the reading upon getting its maximum reading. The same procedures was repeated with different positions; at one end of the coil, and at 15 cm away from the center of the coil along the axis of the coil. All the measurements was deleted after getting the maximum readings. Next, the voltage knob was adjusted to double the value of the current displayed in the power supply. Then the procedures was repeated from clicking the start button up to different positions. Lastly, the results was recorded in the worksheet, and all the measurements was deleted.

III. Results and Discussions Part A. Magnetic induction When the magnet was placed inside the coil with no movement, the voltmeter reading was zero. This explains Faraday’s Law on Electrical Induction stating that movement causes magnetic flux in the magnetic field which induces electrical energy. The same reading was observed when the magnet was placed 5 cm away from the coil. From this we can imply that the distance of the magnet had no effect on the magnetic field as motion is what causes magnetic flux on the magnetic field. On the contrary, when the magnet was slowly moved in and outside of the coil, the voltmeter had read changes in voltage. The movement of the magnet induced electromotive force, though the voltage reading reading was low. When the magnet was moved faster, the voltmeter had a higher reading compared to when the magnet was moved in a slow manner. This is due to the fact that an increase in the motion of a magnet causes stronger force of magnetic lines on the free electron present on the conductor, generating a stronger current. How powerful the flow of an electron is, can be solved using the equation: e= B*l*v where “l” is the length of the conductor, “B” as the strength of the electromagnetic field and “v” as the velocity of the conductor. This equation s our claim that an increase in the velocity produces higher electromotive force or EMF.

Part B. Measurement of Magnetic Field at different points around a Bar Magnet

Figure1, Five different locations where to measure the magnetic field.

Magnetic Probe Position

Magnetic Field (mT)

At point A

24.3

At point B

-4.0

At point C

8.9

At point D

8.9

At point E

4.5

The magnetic field surrounding the magnet was measured at different magnetic field vectors for us to locate the direction of the magnetic field and in which direction the magnetic field is most intense. This also tells us something about its effect on the electrical particle ing in these points. Upon placing the magnetic probe at point A, we observed that it has the densest or strongest magnetic field which was 24.3mT as it is closest to the magnet. Moreover, the positive sign that was observed indicates that the magnetic field that was measured was near the north pole. Conversely, when the magnetic probe was placed at point B, it showed the least dense magnetic field which was -4.0mT and showed a negative sign indicating that it is near the south pole. At points C and D, we observed the same intensity in their respective magnetic field, both 8.9mT. This similar result could be due to the similarity of their this distance and angle away from the bar of magnet. Their decrease in intensity compared to point A has to do with their distance from the magnet. Since they were placed farther, the intensity of the magnetic field decreased. This also suggests that at this point, there is lesser magnetic lines that penetrated the area. In other words, there is lesser magnetic flux. Lastly, at point E, the magnetic field was observed to be the least dense among points A, C and D since it is farthest from the magnet. Magnetic flux density diminishes with increasing distance. Point E, therefore has the least dense magnetic flux.

Part C. Measurement of Magnetic Field of an Electromagnet ( a current-carrying coil ) Voltage: 2.5 V

Voltage: 4.9 V

Current: 0.207 A

Current: 0.414 A

Magnetic Field (mT)

Magnetic Field (mT)

At the center of the coil

8.9 mT

13.6 mT

At one end of the coil

6.2 mT

8.4 mT

15.0 cm away from the center of the coil

4.8 mT

4.8 mT

The strength of the magnetic field will vary from the distance of the magnet to the coil. The further it is from the coil the strength of the magnetic field will be weaker. Upon observation when the current was doubled, the different distances also increases its value. The magnetic field strength of the electromagnet also depends upon the type of core material being used as the main purpose of the core is to concentrate the magnetic flux in a well defined and predictable path.

IV. Conclusions

When the magnet is command stationary at that position, the meter returns to zero position. currently once the magnet moves removed from the coil, there's some deflection within the voltmeter however other way, and once more once the magnet becomes stationary, at that time relevancy the coil, the meter returns to the zero position. Similarly, if the magnet is command stationary and therefore the coil moves away, and towards the magnet, the meter equally shows deflection. it's contly seen that the quicker the amendment within the force field, the bigger are the induced voltage or voltage within the coil. We also noticed that the magnetic field of a permanent magnet is not uniform.The strength of the field varies looking on its location around the magnet. The field of a magnet is strongest at either

pole of the magnet. it is equally strong at the north pole compared with the south pole. The force is weaker within the middle of the magnet and halfway between the pole and the center.The field lines are closely packed at either pole of the magnet, widening as they get beyond the pole and connecting to the other pole of the magnet. The field of force lines emerge from the pole and enter the South Pole. The field of force gets weaker the more you get from either pole

At the end we presume that the investigation has worked out quite well and we gathered the expected results. The strength of the magnetic field is dependent on the voltage produced by the electric current. When the magnetic probe was slowly moving away from the coil the magnetic field decreases and if the electric current is doubled the magnetic field doubles as well because they are directly proportional to each other. The results were in truth adequate enough to bring us to a firm conclusion. however even supposing my prediction was right we tend to still received results that weren't quite expected. this can be because of the errors that were created in recording the results. we tend to failed to record the results properly as a result of there have been either pins hanging off or ed along. We can improve the investigation by acting every experiment two or three times rather than simply once to form it even fairer. still as being honest the investigation can gain us very accurate results to point out. we have a tendency to might additionally improve the investigation by using numerous sorts of conducting wires.

References 1. Young, H. and Freedman-Sears, R. (2012). University of Physics. 13th ed. chapter 29-31. San Francisco, USA: Pearson Education, Inc., Publishing as Addison Wesley 2. Electromagnetic Induction(n.d.): Definition, Applications, Laws, Videos. from Topprguides:https://www.toppr.com/guides/physics/magnetic-effects-of-electriccurrent/electromagnetic-induction-and-itsapplications/?fbclid=IwAR2auP7mu_SclKkP7UXbUTRl3u_NfmKErjAQNPDlvaAcez7PL 8z0fUfQ9qY. (Not published)

3. Copyright

Center:

Induction

and

Electromagnetism(n.d.).

from

Edisontechcentre.org:http://edisontechcenter.org/InductionConcept.html?fbclid=IwAR0I xmpdz7XwoAFllcTyCZaxQ3N-jZDY3QlbNqPUkud7HmjWGei1FThfbxw. (Not published) 4. Electromagnetic

Induction(n.d.).

from

Nde-ed.org:https://www.nde-

ed.org/EducationResources/HighSchool/Electricity/electroinduction.htm?fbclid=IwAR12 d933aTSXJXPCtD3pbG2XqmP1dBbGylMFDsccTJOv1eUNqqbFdPE3q7U.

(Not

published) 5. What mean.

What does magnetic vector

mean?(n.d.) from Physics Stacks

Exchange:https://physics.stackexchange.com/questions/179055/what-does-magneticfield-vectormean?fbclid=IwAR11LvEe_2jotyPx5axw9etNQ5SYyTiS4NMQP54ffQgzX1WSYa5JQsXqf0. (Not published) 6. The

Power

of

Electromagnets

-

Conclusion(n.d.).

from

Odec.ca:http://www.odec.ca/projects/2010/bosaxa2/conclusions.htm?fbclid=IwAR3K17h 9jM9JEk4uXEa85xJ8ZecZzwQOgF2Anomwk7KOx7h4ftz4Fpcj10U. (Not published)