Good Experimental Features Flashcards
General Good Practices (1)
- Repeat measurements are taken (of y-variable) are taken and the average found. (This is a general feature)
General Good Practices (2)
A preliminary experiment is done to get an idea of the (i) Rebound height of the ball (ii) the range of load to be used.
General Good Practices (3)
Use a large ….. so as to produce a measurable (quantity of small magnitude, hence hard to measure accurately.) Eg. A large B-field to produce a measurable induced e.m.f.
Magnetic Experiment
Ensure no other magnetic substances are nearby.
Oscillation Experiment
Ensure the room is draught-free.
Use a large number of oscillations.
Sound Experiment
Use a room which is relatively sound proof.
The intensity of sound should be maintained at a constant value.
The sound source should be placed at a fixed distance form the detector.
Light Experiment
Ensure that the room is partially or totally dark as required. A darkened tube/container may sometimes replace a dark room.
Intensity of light source may need to be constant.
Distance between light source and detector may need to be maintained at a constant value.
Heat Experiment
Ensure good insulation between apparatus and environment by using a good lagging material.
Always state that a steady state is achieved before taking temperature measurements.
Ensure uniform distribution of heat in liquid by continuous stirring.
Ensure uniform distribution of heat in liquid continuous stirring.
Method to ensure temperature of system is uniform:
- Use an oven with thermostat to maintain constant temperature.
- Heat the system in a water bath (if appropriate)
Radioactivity Experiment
Subtract background count rate from measured count rate to obtain true count rate.
The source might need to have a long half-life (so that its activity will not decrease significantly during the experiment.
Radioactivity Safety Precautions
Use a source-handling tool e.g. tweezers or tongs.
Do not point the source at people/don’t look directly at the source.
Store the source in a lead-lined box when not in use.
“Wear protective clothing, lead suits, lead gloves, goggles” not accepted.
Electricity Experiment
Switch off power supply between readings to prevent overheating of apparatus.
General Safety Precautions
Wear protective goggles for the eye for intense light or ultraviolet source; protection against flying fragments; ear plugs for loud, explosive experiments.
Use tongs or forceps for hot, radioactive or corrosive materials.
Use a safety screen around safety chamber for low or high pressure experiments.
