An air-filled parallel-plate capacitor has a capacitance of . The separation of the plates is doubled and wax is inserted between them. The new capacitance is . We have to find the dielectric constant of the wax.

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It is given that an air-filled parallel-plate capacitor has capacitance

When the separation between the plates is doubled, the capacitance of the capacitor will change to

It is given that now when wax is inserted between the plates of the capacitor its capacitance changes to

We know that when material with dielectric constant is inserted inside a capacitor the relation between the capacitances is

Therefore,