nota precaution step

PHYSICS SPM -PRECAUTIONARY STEPS FOR INVESTIGATIVE EXPERIMENTS

No.	Type of experiment involving	Precautions that can be taken
1	Light	-Experiment must be carried out in darkened room. -Lens, screen and object must be in line  -Avoid parallax error by placing the eye such that the line of view is perpendicular to the scale of the ruler.
2	Spring	-make sure the spring is not loaded beyond the elastic limit. (spring return to original length when load is taken off). -Avoid parallax error by placing the eye such that the line of view is perpendicular to the scale of the ruler.
3	Electric	-All connections must be secure/tight. -Off the switch after readings are taken to prevent wires from heating up (resistance increase) -Avoid parallax error by placing the eye such that the line of view is perpendicular to the scale of the ammeter/ voltmeter.
4.	Heat	-Liquid must be stirred constantly so that temperature rises evenly. -Aluminium block must be wrapped with insulating material to prevent heat lost. -Thermometer bulb should be smeared with oil to give better thermal contact with the block. -Avoid parallax error by placing the eye such that the line of view is perpendicular to the scale of the thermometer.
5	Measuring instruments such as ammeter, voltmeter, metre rule ...	-Avoid parallax error by placing the eye such that the line of view is perpendicular to the scale read. -Take into account zero error of instrument.