Zaymiey

⚛️ Physics  ·  Units and Measurements  ·  NEET & JEE

A physical quantity Z is calculated as Z = A²B³/C, where A, B, and C are measured with relative errors of 1%, 2%, and 3% respectively. What is the maximum percentage error in Z?

Answer: 11%.

  • A 7%
  • B 8%
  • C 11%
  • D 13%

Correct answer: C. 11%

Explanation: By the power rule for combination of errors, ΔZ/Z = 2(ΔA/A) + 3(ΔB/B) + 1(ΔC/C) = 2(1%) + 3(2%) + 1(3%) = 2% + 6% + 3% = 11%. Errors in the denominator's quantity still add, since this gives the worst-case (maximum possible) error.

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.

Read the full Units and Measurements notes →