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⚛️ Physics  ·  Units and Measurements  ·  NEET & JEE

Two quantities A and B have different dimensions. Which of the following operations can still be dimensionally valid?

Answer: A/B, since division of differently dimensioned quantities is allowed and gives a new dimensioned quantity.

  • A A + B, since addition is generally defined for any two physical quantities regardless of dimension
  • B A/B, since division of differently dimensioned quantities is allowed and gives a new dimensioned quantity
  • C A - B, since subtraction is generally defined for any two physical quantities regardless of dimension
  • D sin(A/B), provided A and B individually have nonzero dimensions

Correct answer: B. A/B, since division of differently dimensioned quantities is allowed and gives a new dimensioned quantity

Explanation: Multiplication and division of quantities with different dimensions are valid and yield a new physical quantity, whereas addition or subtraction requires both quantities to share the same dimensions, and trigonometric functions require dimensionless arguments.

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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