Two metallic plates form a parallel plate capacitor. The distance between the plates is 'd'. A metal sheet of thickness $${d \over 2}$$ and of area equal to area of each plate is introduced between the plates. What will be the ratio of the new capacitance to the original capacitance of the capacitor?

If the charge on a capacitor is increased by 2 C, the energy stored in it increases by 44%. The original charge on the capacitor is (in C)

A parallel plate capacitor is formed by two plates each of area 30$$\pi$$ cm² separated by 1 mm. A material of dielectric strength 3.6 $$\times$$ 10⁷ Vm^$$-$$1 is filled between the plates. If the maximum charge that can be stored on the capacitor without causing any dielectric breakdown is 7 $$\times$$ 10^$$-$$6C, the value of dielectric constant of the material is :

[Use $${1 \over {4\pi {\varepsilon _0}}} = 9 \times {10^9}$$ Nm² C^$$-$$2]