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If a capacitor has capacitance C and the charge on its plate is Q, what is the dimensional formula of Q²/C?

1. [L²M²T]
2. [LMT²]
3. [L²MT⁻²]
4. [L²M²T⁻²]

Correct answer: [L²MT⁻²]

Solution

Energy stored in a capacitor is U = Q^2/(2C), so Q^2/C has the dimensions of energy = [M L^2 T^-2]. The correct option is [L^2 M T^-2].

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