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GATE 2026 IN – Question 49

Measurements · Voltage current and power measurement · 2 marks · Multiple choice

If the definition of SI unit X is required to define SI unit Y, the dependency is indicated as X → Y. A valid order of dependencies, as per present convention, is ________.

  1. metre → second → kilogram → kelvin
  2. second → metre → kilogram → kelvin
  3. metre → second → kelvin → kilogram
  4. second → kilogram → kelvin → metre

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Show answer and explanation

Correct answer: (B) second → metre → kilogram → kelvin

Explanation

The second is defined using the caesium transition frequency. The metre uses the fixed speed of light with the second. The kilogram uses the fixed Planck constant, whose units involve the metre and second. The kelvin uses the fixed Boltzmann constant and the resulting mechanical energy units.

The dependency order is therefore **second → metre → kilogram → kelvin (B)**.