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Units And Measurement

Question
CBSEENPH11020287

Let [ε0] denote the dimensional formula of the permittivity of vacuum. If M = mass, L = length, T = time and A = electric current, then

  • 0] = [M-1L-3T2A]

  • 0] = [M-1L-3T4A2]

  • 0] =[M-2L2T-1A-2]

  • 0] = [M-1L2T-1A2]

Solution

B.

0] = [M-1L-3T4A2]

From Coulomb's Law, F
straight F space equals space fraction numerator 1 over denominator 4 πε subscript straight o end fraction fraction numerator straight q subscript 1 straight q subscript 2 over denominator straight R squared end fraction
straight epsilon subscript straight o space equals space fraction numerator straight q subscript 1 straight q subscript 2 over denominator 4 πFR squared end fraction
On Substituting the units, we get

straight epsilon subscript straight o space equals space fraction numerator straight C squared over denominator straight N minus straight m end fraction space equals space fraction numerator left square bracket AT right square bracket squared over denominator left square bracket MLT to the power of negative 2 end exponent right square bracket left square bracket straight L squared right square bracket end fraction space left parenthesis 4 straight pi space is space dimensionless right parenthesis
space equals space left square bracket straight M to the power of negative 1 end exponent straight L to the power of negative 3 end exponent straight T to the power of 4 straight A squared right square bracket