The capacity of a condensor in which dielectric of dielectric constant 5 has been used, is C. If the dielectric is replaced by another with dielectric constant 20, the capacity will become

Explanation

The capacitance of a capacitor is given by the formula C = ε₀ε_rA/d, where ε₀ is the permittivity of free space, ε_r is the relative permittivity (dielectric constant), A is the area of the plates, and d is the distance between them. When the dielectric constant changes from 5 to 20, the capacitance increases proportionally. Since 20/5 = 4, the new capacitance will be 4 times the original, hence 4C.Options C/4 and C/2 are incorrect because they suggest a decrease or insufficient increase in capacitance, which is contrary to the increase in the dielectric constant. Option 2C only accounts for a doubling, not the quadrupling calculated.