Electromagnetic Induction Experiment 1d3j35

Experiment 9: Electromagnetic Induction Laboratory Report Department of Mathematics and Physics College of Science, University of Santo Tomas España, Manila, Philippines II. Theory Abstract The purpose of the experiment is to determine how the production of current in the presence of a magnetic field.

A magnetic field is produced by electrical currents which could be found in wires or it could be associated with the currents produced by an electron orbiting an atom in accordance with the Lorentz Force Law. In symbols,

Equation 2.0 Lorentz Force Law

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Where F = Force E = Electric field q = electric charge v = velocity of the charge B = magnetic field

Introduction

In 1831, Michael Faraday, an English physicist, performed a series of experiments to determine whether currents are produced in a magnetic field. He found out that when a stationary magnet is placed inside a coil of wire, it will not produce any current. He later realized that a sudden push or pull of pole of magnet inside the coil produces current as evidenced by the deflection of the needle of a galvanometer. Faraday’s Law of Electromagnetic Induction is perhaps considered to be the most important concept in electromagnetism as it bridges the gap between electricity and magnetism. Absence of this law will also lead to the absence of modern electronic gadgets such as television, generators, radios, telephones, and others to name a few. Hence, the objectives of the experiment are to determine how current is induced in a coil of wire, to identify the factors affecting the induced current, and to verift Lenz’s Law.

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Methodology

In the experiment, two coils of wire was used. In the first coil, there are 100 turns of wire. The magnet was then placed inside the coil facing its north pole. The coil was connected to galvanometer having a scale of -10 to +10 and -5 to +5 between it. The magnet was then quickly pulled against the coil and the deflection of the needle of the galvanometer was recorded. The same was done with the south pole of the bar magnet. The deflection of the needle of the galvanometer was also recorded. In the second coil, having 50 number of turns, a bar magnet was placed in the middle of the coil. Each pole was placed and then quickly pulled against the coil. The deflection of the galvanometer for each pole was recorded.

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Results and Discussions

Table 4.0 Deflection of galvanometer 50 100 Number of turns of coil North

5 towards 10 towards the negative the negative

South

5 towards 10 towards the positive the positive

Table 4.0 shows the amount of deflection of the galvanometer corresponding to the number of turns in a coil of wire.

A full-scale deflection of a galvanometer is usually small, about 10µA. To determine the accurate amount of current, a shunt resistor must be connected in parallel with the galvanometer. From the table, in the 50 number of turns of a coil of wire, same amount of current was observed to both poles when it was quickly pulled but in different directions. In 100 number of turns of a coil, both poles deflect the same amount of current but in different directions. This corresponds to the fact that when the number of turns increases, magnetic field becomes stronger which makes the current also stronger. V.

In Table 4.0, it is clearly manifested that a change in the number of turns of wire will correspond to the amount of current it will produce. This factor stems from the fact that the magnetic field strength is directly proportional to the current that will be produced.

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References [1] Halliday, Resnick & Walker. (1997). Fundamentals of physics. New York, NY: Wiley. [2] Knight, R. (2009). Physics for scientists and engineers: Volume 4. New York, NY: Cengage Learning. [3] Griffiths, D. (2012). Introduction to electrodynamics. New York, NY: Addison-Wesley.

Conclusions

From the experiment, it is highly evident that the current is induced when there is a sudden change of a magnetic field. Repeating the same procedure with a different number of turns of wire, the galvanometer still deflects its needle. This is similar to what Faraday had discovered which states that an electric will produce if a magnetic field is in relative motion.

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