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⚛️ Physics  ·  Units and Measurements  ·  NEET & JEE

A wire's resistance is calculated using R = V/I, where V and I are read off analog meters. The voltmeter reading is 5.0 ± 0.1 V and the ammeter reading is 2.0 ± 0.05 A. The resistance, with its absolute error, should be reported as:

Answer: 2.5 ± 0.1125 Ω.

  • A 2.5 ± 0.05 Ω
  • B 2.5 ± 0.15 Ω
  • C 2.5 ± 0.025 Ω
  • D 2.5 ± 0.1125 Ω

Correct answer: D. 2.5 ± 0.1125 Ω

Explanation: Relative error in R = (0.1/5.0) + (0.05/2.0) = 0.02 + 0.025 = 0.045, so absolute error = 0.045 × 2.5 = 0.1125 Ω.

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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