Important Questions on Physical Quantities and Measurement-1
Define length. Name three instruments used to measure it. 
Name multiples and submultiples of metres and their relation with the metre. What is parallax error? How can it be avoided? What do you understand by area? Give its standard unit in the SI system. Name the instruments used to measure mass. What are the precautions that are needed to be taken while measuring the length of a wooden block using a metre scale? Write a short note on beam balance. Explain how the department of weights and measures, Government of India, is helping people so that they would not get cheated by the shopkeepers. 
