Precaution for Paper 3 as i promised

Measuring Instrument
a. Avoid parallax error by placing the eye such that the line of view is perpendicular to the scale read. ( for ammeter/voltmeter/measuring cylinder etc)
b. Take into account zero error of instrument. (for calipper/micrometer/weight scale etc.)

Spring/Hookes Law
a. make sure the spring is not loaded beyond the elastic limit.(spring return to original length when load is taken off).
b. Avoid parallax error by placing the eye such that the line of view is perpendicular to the scale of the ruler.

Heat
a. Liquid must be stirred constantly so that temperature rises evenly.
b. Alluminium block must be wrapped with insulating material to prevent heat lost.
c. Thermometer bulb should be smeared with oil to give better thermal contact with the block.
d. Avoid parallax error by placing the eye such that the line of view is perpendicular to the scale of the thermometer.

Light
a. Experiment must be carried out in dark room.
b. Lens, screen and object must be in line
c. Avoid parallax error by placing the eye such that the line of view is perpendicular to the scale of the ruler.

Electricity
a. All connections of wire & other device must be tight.
b. Off the switch after readings are taken to prevent wires from heating up (resistance increase)
c. Avoid parallax error by placing the eye such that the line of view is perpendicular to the scale of the ammeter/ voltmeter