Question

Which one of the following is the correct dimensional formula for the capacitance in F? M, L, T, and C stand for unit of mass, length, time, and charge.

• A. \( [CM^{-1}L^{-2}T^2] \)
• B. \( [C^2 M^{-1} L^{-2} T^{-2}] \)
• C. \( [C^2 M^{-1} L^2 T^{-2}] \)
• D. \( [C^{-2} M^{-1} L^2 T^{-4}] \)

Hint:

To determine the dimensional formula of capacitance, use the relationship \( C = \frac{Q}{V} \), and express the units of \( Q \) and \( V \) in terms of mass, length, time, and charge.

Answer 1

The Correct Option is A

The capacitance \( C \) is defined as the ratio of charge \( Q \) to potential difference \( V \), expressed by the equation: \[ C = \frac{Q}{V} \] The unit for charge \( Q \) is coulombs \( [C] \). The unit for potential \( V \) is derived from \( V = \frac{U}{Q} \), where \( U \) (Joules) represents energy. The dimensions of energy are \( [M L^2 T^{-2}] \). Therefore, the dimensions of potential are: \[ V = \frac{[M L^2 T^{-2}]}{[C]} \] Consequently, the dimensional formula for capacitance is: \[ C = \frac{[C]}{[M L^2 T^{-2}] [C]} = [CM^{-1}L^{-2}T^2]. \] The correct answer is \( \boxed{[CM^{-1}L^{-2}T^2]} \).