Skills of Experimental Physics

The psychomotor domain of learning physics subject primarily comprises of acquiring experimental skills. Experiments are attempts made in the laboratory to replicate the events of nature in a controlled manner. 

Such attempts provide proofs to the claims and predictions made in physical theories and further extend the frontiers of the subject. This article tries to gain further insight on this topic.

Ten Skills of  Experimental Physics:

1.Observation: We observe that a body thrown upwards fall down quickly.

2.Hypothesis: We guess that bodies thrown upwards are pulled down by the earth using gravitational force and hence an acceleration due to gravity g must act on any body of certain mass thrown upwards.

3.Operational Definition: To verify this guess, we need to come up with a mechanism of action. Theoretically, a bob of  point mass when made to oscillate from a hook using a weightless string of length l has a time period T = 2*π*√l/g.

4.Experiment: We design an experiment where a small bob and a thread of very less weight are taken. The bob is made to hang from the hook of  a stand. It is made to oscillate and a table clock is used to calculate the time for 20 oscillations say.

5.Controlling Variables: Here the time periods of the bob’s oscillations are noted for different lengths of the thread. The amplitude is kept small and the bob is not allowed to wobble.

6.Measurement: The readings of the time period for 20 oscillations in secs for each length of the thread 5cms apart are tabulated.

7.Use Space-Time Relationships: From the relation T = 2*π*√l/g, we have g = 4*π²*l/T².

8.Interpretation of Data: When a graph is drawn with l on x-axis and T² on y-axis, we get a straight line passing through the origin, each set of values. The slope of the straight line in each of the set of values of l and T²is equal to (4*π²) / g. In this way, the value of  acceleration due to gravity is calculated as 980 cms / sec².

9.Prediction: From the analysis, it reveals that l and T² are directly proportional to each other. The mass of the object does not have a role to play. Increase or decrease in the length of weightless string changes the time period of oscillations accordingly.

10.Inference: Every body on earth, irrespective of its mass, experiences an acceleration due to the gravitational force which is quantatively equal to 980 cms/ sec².