EXP: Measuring Instrument
- 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)
- Take into account zero error of instrument. (for caliper / micrometer / weight scale etc.)
Exp: Spring / Hookes Law
- 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.
Exp: Heat
- Liquid must be stirred constantly so that temperature rises evenly.
- Alluminium 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.
Exp: Light
- Experiment must be carried out in dark 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.
Exp: Electricity
- All connections of wire & other device must be 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.
*NOTE
The below precautions are often written in exams:
- eyes must be perpendicular to the scale to avoid parallax error.
- repeat the experiment and find the average
