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JEE Main 2015 Physics question

PhysicsUnits and MeasurementJEE Main 2015

If electronic charge , electron mass , speed of light in vacuum and Planck's constant are taken as fundamental quantities, the permeability of vacuum can be expressed in units of:

Answer: (4)

Solution

Start from the fine-structure constant, which is dimensionless: . This tells us has the same dimensions as . Since , we get — option (4). A direct dimensional check

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Question ID VK-115316