Physics
During a Physics practical, Ayush and Reema measured the length of a metal rod using two measuring instruments A and B. Ayush used instrument A and obtained a reading of 25.4 cm, while Reema used instrument B and obtained a reading of 25.36 cm.
(a) Why did Ayush and Reema get different values for the same length?
(b) Which measuring instrument is more accurate, A or B?
(c) Can you identify the measuring instruments A and B?
(d) Why is it important to use S.I. units while recording measurements?
Measurements
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Answer
(a) Ayush and Reema obtained different values because the two instruments have different least counts (precision) and an instrument with a larger least count measures only up to fewer decimal places, while a more precise instrument can measure smaller fractions of a unit. Therefore, the readings differ even though the length is the same.
(b) Instrument B is more accurate because its reading (25.36 cm) is given up to two decimal places, indicating a smaller least count and higher precision than instrument A.
(c) Instrument A is likely a metre scale (or ruler), which usually measures up to 0.1 cm and instrument B is likely a vernier caliper, which can measure more precisely, typically up to 0.01 cm.
(d) It is important to use S.I. units while recording measurements because they provide a standard and internationally accepted system of units which ensures that measurements are uniform, consistent and easily comparable anywhere in the world.
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