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A parallel-plate capacitor is charged by a battery and then the battery is removed and a dielectric of constant K is used to fill the gap between the plates. Inserting the dielectric changes the energy stored by a factor of

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Answer:

Explanation:

Battery is removed so its charge stored Ā becomes fixed .

Energy of capacitor E₁ = Q² / 2C

When dielectric is inserted , the capacity of the capacitor is increased to KC .

Charge on it still remains the same ie Q

So its new energy

Eā‚‚ = Q² / 2 KC

Eā‚‚ / E₁ = 1 / K

Eā‚‚ = E₁ / K

Change in energy

= Eā‚‚ - E₁

= E₁ / K - E₁

= E₁ [ (1 / K) Ā - 1 ]

Factor by which energy is changed

= [ (1 / K) Ā - 1 ] .