Apparatus:
Retort stand/clamp/boss, metre ruler, mounted LDR, 12V light bulb, power supply for the light bulb, multimeter used as an ohmmeter, connecting wires.
Hypothesis:
A student suggests that the difference in resistance,
of a LDR (light-dependent-resistor), when a light source is switched on and off, will be inversely proportional to the square of its distance away from a light source; i.e.![]()
The student uses the following argument to support the above hypothesis:
The intensity,
of light from a source is inversely proportional to the square of the distance from the source; i.e.![]()
The student then states that the change in resistance,
of an LDR is proportional to the change in intensity of light falling on it i.e.![]()
Combining these two relationships results in the claim that![]()
Experiment:
Use the apparatus supplied to test out the student's hypothesis.
Your write up should include:
(a) a simple diagram showing how you used the apparatus
(b) a table of results and / or a relevant graph
(c) a clear explanation of how you used your results to confirm or refute the hypothesis that![]()
(d) an account of any precautions you took in order to obtain good results.