Errors

by bpearson on March 4, 2010 · 0 comments

in Resources & Tips

I. INTRODUCTION: Observations are taken in the laboratory and from these observations certain conclusions are drawn. Since no observation or series of observations is absolutely accurate, it is often desirable to check the dependability of the conclusions by a study of the errors in the experiment.

Suppose that an experiment on the relation between the pressure and volume of a gas is performed in the laboratory and that the conclusion is the statement of the law that the volume is inversely proportional to the pressure. The experiment does not prove that the law is absolutely accurate but only that within certain limits, determined by the accuracy of the experiment, it has been found to be true. Small departures from the law will always be found and it should be possible to determine whether these departures indicate that the law is not exactly true or whether they are due to unavoidable experimental errors. Even if in this experiment no significant departures were found, observations with more refined apparatus might show conclusively that the law was only an approximation to the truth.

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Charles’ Law – Experiment One

by bpearson on March 2, 2010 · 0 comments

in Lesson Plans

OBJECT: To study the expansion of gases, to check Charles’ law and to measure the temperature coefficient of pressure increase of dry air at constant volume.

METHOD: Charles’ law for the expansion of gases is studied by the use of a simple form of constant-volume air thermometer. A fixed volume of dry air is subjected to certain measured temperatures and the corresponding pressures observed. From the resultant pressure-temperature curve the temperature coefficient of pressure increase at constant volume is determined. By extrapolating this curve the value of “absolute zero” is determined approximately.

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Centripetal Force by Graphical Induction

February 28, 2010 Lesson Plans

OBJECT: To determine empirically the functional relationship of the centripetal force (a) to the mass of the moving body, (b) to its tangential velocity and (c) to the radius of the circular arc in which the mass moves.
METHOD: The centripetal force acting on a pendulum bob, when the bob passes across its rest position, is [...]

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Centripetal Force

February 26, 2010 Lesson Plans

OBJECT: To make a study of the motion of a body traveling with constant speed in a circular path, and to verify the expression for centripetal force.
METHOD: By means of an electrically driven rotator a body of known mass is rotated about a vertical axis in such away as to produce a definite extension of [...]

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Boyle’s Law – Experiment 3

February 24, 2010 Lesson Plans

OBJECT: To study Boyle’s law, at moderate pressures above and below atmospheric, by both analytical and graphical methods.
METHOD: A fixed mass of air confined in a glass tube is kept at room temperature and subjected to various pressures, ranging from half to double atmospheric pressure. A series of corresponding pressures and volumes are observed and [...]

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Boyle’s Law – Experiment 2

February 22, 2010 Lesson Plans

OBJECT: To study Boyle’s law, at moderate pressures above and below atmospheric, by both analytical and graphical methods.
METHOD: A fixed mass of air confined in a glass tube is kept at room temperature and subjected to various pressures, ranging from half to double atmospheric pressure. A series of corresponding pressures and volumes are observed and [...]

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