# Introduction to Physics Lab

## Introduction

Electricity and magnetism are interesting phases of physics. The aspects are very familiar in our daily life when it comes to the occurrence of static cling where when two objects, for example, a woolen cloth and saran wrap are ribbed together, they stick. This is interpreted in terms of electric charge. The objects acquire electric charge and that is why they cling. Electric charge has the following characteristics. There are two types of charge, which by convention are labeled positive and negative. Like charges repel, and unlike charges attract, and all objects may have a charge equal to an integral number of a basic unit of charge. In addition, charge is never created or destroyed.                                                                                                                                              The relationship between electricity and magnetism is called electromagnetism. Both are strong forces of nature (Ford, 2010). The perception of describing electricity and magnetism forces is the electric field.  The force on a charge rests on the magnitude of the charges, which are associated. The distance which separates charges also influences the force on a charge. The electric field differs from one point to another in both magnitude and direction. The direction of an electric field at one point is still the direction of the force on a positive test charge put at the point. That is by convention. The magnetic poles are of two types, namely; the north and south poles. The like poles repel while the unlike poles attract. This attraction, however, differs from electric power in the sense that unlike electric charges, magnetic poles always occur in North-South pairs; there are no magnetic monopoles. It is difficult to explain the interaction of electricity and magnetism in nontechnical terms.  This is mainly because one has to define the connections in terms of invisible “force fields” which shift, expand, contract, strengthen, weaken, and rotate in space. It is not easy to explain the concepts sufficiently in verbal terms.  In terms of mathematics, coupled sets of three-dimensional vector differential equations are vital and they are also quite difficult to visualize (Perkins, Perkins & Perkins, 2007).

Historical events and annotation

1. 1700: demonstrations and lectures were provided by different scientists by utilizing electricity so as to entertain and attract audiences.
2. 1747: Ben Franklin made a discovery that there existed two forms of charges; negative and positive and that while unlike charges attract, like ones repel. Franklin also documented ‘conservation of charge’; isolated systems have constant total charge. This information was essential for progress in electromagnetism (Kivelson & Russell, 2005).
3. 1785; the Coulomb Law was documented by Charles Austin de Coulomb. He proved that the force existing between two charges was proportional to the product divided by separation distance r squared. He also discovered the ‘inverse square law.’ This information was extremely useful to the academic sector.
4. 1780; Luigi Galvani made the discovery that electricity emerging from two differing metals made the legs of frogs to twitch.
5. 1790; Alessandro Volta discovered that if chemistry is acting on 2 different metals, electricity is generated. Later, he invented the voltaic pile battery.
6. 1820: it was discovered by Hans Christian Oersted that a compass needle is affected by electric current.
7. 1873: the ‘Treaty on Electricity and Magnetism’ was published by Maxwell in which he summarized and synthesized the discoveries made by Faraday, Ampere, Oersted, Coloumb et al. in 4 mathematical equations (Serway, Beichner & Jewett, 2011). The equations are presently used as a electromagnetic theory basis. Maxwell also made a prediction of electricity and magnetism that directly lead to electromagnetic waves prediction.
8. 1885; Heinrich Hertz indicated that Maxwell was indeed correct. He generated and detected electromagnetic waves.
9. 1895; Guglielmo Marconi tried the discovery practically through sending messages over large distances by using radio signals, that is, the Wireless.

Conclusion

Presently, scientists study electromagnetism through researches. Numerous scientific studies were conducted and in addition to the study on Environmental Protection Agency (1990) ‘An Evaluation of the Potential Carcinogenecity of Electromagnetic Fields (ELF)’, important links were identified between cancer in humans and exposure to ELF. In the 1950s, ionosphere research began and in supporting this research, a 5-country consortium is in charge of the European Incoherent Scatter Radar ionospheric research site in Norway (Fernow, 2009).

Electromagnetism has resulted to a revolution in engineering, construction, space, and medicine. Every powered device in use from microwave ovens to table clocks possesses some kind of electromagnetism principle that is responsible for its functioning. As a result of electromagnetism, there is the flexibility of switching on/off electricity. An electromagnet’s strength depends on the degree of current that is passing via the conductor. The current can also be started or stopped to create an electromagnet as well as de-energize respectively depending on the tasks to be done (Serway, Beichner & Jewett, 2011). This is the principle utilized in a scrap yard to move heavy objects. The modern day trains that are presently in operation in Germany and Japan are largely reliant on electromagnetic principle.

Can a knitting needle grow since solids expand when heated?

If a person heats his pairs of hands and places them on a bottle containing gas, the generated heat is adequate to expand the gas considerably. However, solids expand much less compared to gases if there is a particular temperature increase (Serway, Beichner & Jewett, 2011). This experiment will use a sensitive but simple device for observing a knitting needle expanding if heated using a candle. Since sharp objects and naked flames will be used in the experiment, it will be performed as a demonstration.

The expansion of solids is applicable to many areas in life. For instance, when hanging telephone wires, they are slack if the weather is a hot summer so that the telegraph poles are not pulled over following contraction in winter. Second, when laying concrete roads, there are soft pitches in between some sections. Cooking glass should have a low expansion, for example Pyres, so as to ensure it does not shatter after getting hot. Air friction is used to warm high-speed planes, which makes them longer (Serway, Beichner & Jewett, 2011).

On the same note, after rocks in deserts crack, the bits fall off after which they become sand. Before putting rivets in place, they are heated so than they can be able to hold metal plates together. Bridges and girders in building should have gaps in the ends so as to leave a space for expansion and contraction. Metal rods can be used to hold old buildings together.

Materials

Metallic knitting needle

2 empty wine bottles

A cork fitting one bottle

A set of keys for weighing down on one side of knitting needle

Pile of books

Sewing needle (with cylindrical shaft)

Drinking straw

Short candle

Matches

Procedure

1. The cork will be pushed halfway into one bottle.
2. The knitting needle’s sharp end will then pushed into the cork’s side. The knitting needle will be just above the bottle’s rim.
3. The other knitting needle’s end will be laid across the 2nd bottle’s mouth.
4. The sewing needle will be stuck through the straw (drinking), 1/3 way along the length of the straw. The hole will be adequately small so that the straw never ends up loose around the needle.
5. With the straw attached, the sewing needle will be places across the 2nd bottle’s mouth, under the knitting needle; it will be at right angles.
6. The weight (keys) will be hanged on the free knitting needle’s end.
7. Then, the straw will be pointed downwards.
8. The pile of books will be placed between the 2 bottles.
9. The candle will then be placed on top of the books’ pile. The pile’s height will be adjusted to ensure that the candle’s top is around three centimeters from the needle (knitting).
10. The candle will then be lighted and observations made.

Heat generated from the candle causes an expansion in the knitting needle. As the knitting needle is expanding, it expands lengthways, moves over and makes the sewing needle to roll (Chaikin & Lubensky, 2000). The sewing needle’s small movements are magnified by the straw.

Based on these findings, other questions that can be addressed include;

1. Since solids expand when heated, can liquids expand?
2. What challenges can heat-related expansion on railways and bridges cause?

References

Chaikin, P. M., & Lubensky, T. C. (2000). Principles of condensed matter physics (Vol. 1). Cambridge: Cambridge university press.

Fernow, R. C. (2009). Introduction to experimental particle physics. Cambridge University Press.

Ford, C. E. (2010). Collaborative construction of task activity: Coordinating multiple resources in a high school physics lab. Research on Language and Social Interaction, 32(4), 369-408.

Kivelson, M. G., & Russell, C. T. (Eds.). (2005). Introduction to space physics. Cambridge university press.

Perkins, D. H., Perkins, D. H., & Perkins, D. H. (2007). Introduction to high energy physics (Vol. 2). Reading, Massachusetts: Addison-Wesley.

Serway, R. A., Beichner, R. J., & Jewett, J. W. (2011). Physics for scientists and engineers with modern physics.