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The electric quantity _____ is equivalent to the mechanical quantity force constant (k).

Asked in GSEB Board March 2020 · Frequency and current in LC

Answer: (4) Reciprocal of capacitance (1/C)

Step-by-step solution

Idea: compare the equation of an LC circuit with that of a mass on a spring.

Spring: m(d²x)/(dt²)+kx=0, with energy 1/2mv²+1/2kx².

LC circuit: L(d²q)/(dt²)+1/C q=0, with energy 1/2LI²+(q²)/(2C).

Term by term: q↔ x, I↔ v, L↔ m and 1/C↔ k.

So the force constant k corresponds to the reciprocal of capacitance, 1/C.

Why the other options are wrong

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