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⚛️ Physics  ·  Units and Measurements  ·  NEET & JEE

A measurement of the speed of light gives values 2.98 × 10<sup>8</sup>, 3.01 × 10<sup>8</sup>, 2.99 × 10<sup>8</sup>, and 3.02 × 10<sup>8</sup> m/s across four trials. Compared to the accepted value of 2.998 × 10<sup>8</sup> m/s, this data set best illustrates:

Answer: Good precision (small spread between readings) along with reasonable accuracy (close to the true value).

  • A Good precision but poor accuracy, since the readings cluster tightly but land far from the true value
  • B Poor precision but good accuracy, since the readings vary widely yet average to the true value
  • C Good precision (small spread between readings) along with reasonable accuracy (close to the true value)
  • D Poor precision and poor accuracy, since the readings neither cluster nor approach the true value

Correct answer: C. Good precision (small spread between readings) along with reasonable accuracy (close to the true value)

Explanation: The four readings are close to each other (high precision) and all lie near the accepted value of 2.998 x 10<sup>8</sup> m/s (high accuracy), so the data set shows both qualities together.

The 7 SI Base UnitsLengthmetre (m)fundamentalMasskilogram (kg)Timesecond (s)Electric Currentampere (A)Temperaturekelvin (K)Amount ofSubstancemole (mol)LuminousIntensitycandela (cd)Every other physical quantity is derived by combining powers of these 7 base units

The 7 SI base units. All derived units (newton, joule, watt, volt, etc.) can be expressed as combinations of these 7 fundamental units raised to various powers.

Concept context

SI base units, dimensional analysis, significant figures, and error propagation. The toolkit every physics calculation relies on.

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