Introduction:
When discussing the nature of charge, it is important to understand that charge comes in discrete units called electrons. Each electron carries a specific amount of charge, and the charge is quantized. However, under certain conditions, the grainy nature of charge can appear to be lost, and it appears to be continuous. This phenomenon is observed in conductors and is known as the "continuity of charge."

Explanation:
The continuity of charge is a concept that describes how charge behaves in conductive materials such as metals. In these materials, the outermost electrons of atoms are loosely bound and are able to move freely within the material. When a potential difference is applied across the conductor, these free electrons begin to flow, creating an electric current.

Conductors and Free Electrons:
In a conductor, the atoms are arranged in a lattice structure, with the outermost electrons participating in the conduction process. These free electrons are not bound to any particular atom and can move freely within the lattice. When a voltage is applied, these free electrons drift in a specific direction, creating an electric current.

Quantization of Charge:
The quantization of charge refers to the fact that charge exists in discrete units called electrons, and each electron carries a specific amount of charge. The charge on a single electron is approximately 1.6 x 10^-19 coulombs. This means that charge cannot be divided into smaller parts and only exists as integral multiples of the electron's charge.

Continuity of Charge in Conductors:
In conductors, such as metals, the presence of a large number of free electrons enables the charge to appear continuous. Although charge is quantized at the microscopic level, the vast number of free electrons in a conductor allows the overall flow of charge to be treated as continuous at the macroscopic level.

Visualizing the Continuity of Charge:
At the microscopic level, individual electrons are still discrete entities with fixed charges. However, when observing the overall flow of charge in a conductor, the movement of these individual electrons is so rapid and random that it appears as a continuous flow of charge. This is similar to how a water current in a river appears continuous, even though it is made up of individual water molecules.

Conclusion:
In summary, the grainy nature of charge is lost and appears to be continuous in conductors due to the presence of a large number of free electrons. While charge is quantized at the microscopic level, the overall flow of charge can be treated as continuous at the macroscopic level. Understanding the continuity of charge is crucial in the study of electrical circuits and the behavior of conductive materials.