DESIGN QUESTIONS
Below are some suggestions on how to go about in designing an experiment. Understand and remember the various instrument used for measuring the quantities, the methods used to produce them and the way to vary them.
Guide for Design Questions
Identify the variables: the independent variable, the dependent variable, and any variables or factors to be kept constant.
Draw a labelled diagram to show the experimental set up.
Ask yourself these questions:
(a) For independent variable: (i) How to produce the variable? (ii) how to vary the variable? (iii) how to measure the variable? (b) For dependent variable: (i) How to produce the variable? (ii) how to measure the variable? (c) What are the variables / factors to be kept constant? How to monitor them so that they are kept constant? (d) What are the safety precautions? (e) How the results are to be analysed? (f) Further good design / experimental features? E.g. any precautions to be taken to improve the accuracy of the experiment, any comment on the difficulties of the experiment, suggestion on how the table to be drawn and the graph to be plotted.
The tables below give suggestions how to measure certain variables. The list given is not exhaustive.
Measurement
Instrument / method
1
(a) Length, distance
(b) Small length
(c) Diameter of a wire, tube
(d) External diameter of a tube
(e) Internal diameter of a tube
(a) Metre rule
(b) Vernier scale, travelling microscope
(c) Micrometer screw gauge (measure 5 times in different places and direction, then take average)
(d)(i) Micrometer screw gauge
(ii) travelling microscope. (Measure in a few different directions and take average.)
(e) (i) Travelling microscope. (Measure in a