Question

An air-filled capacitor stores a potential energy of 6.00 mJ due to its charge. It is accidentally filled with water in such a way as not to discharge its plates. How much energy does it continue to store after it is filled

Answer 1

This question is incomplete, the complete question is;

An air-filled capacitor stores a potential energy of 6.00 mJ due to its charge. It is accidentally filled with water in such a way as not to discharge its plates. How much energy does it continue to store after it is filled?

(The dielectric constant for water is 78 and for air it is 1.0006.)

Answer: it continue to store 0.07692 mJ after it was filled

Explanation:

Given that;

stored potential energy = 6.00 mJ = 0.006 J

dielectric constant for water K = 78

Energy stored  U = Q² / 2C = 0.006 J

C = ∈₀A/d { Air}

C = K∈₀A/d  { Water, k = 78 }

so

U = 0.006 / 78

U = 7.6723 × 10⁻⁵J

U = 0.07692 mJ

Therefore it continue to store 0.07692 mJ after it was filled