What is London force? Give its characteristics.

(N/A) London force: The weak attractive forces present between symmetric atoms or non-polar molecules are known as London forces or dispersion forces.
This force of attraction was first proposed by the German physicist Fritz London, and for this reason, the force of attraction between two temporary dipoles is known as London force.
Characteristics:
- Another name for this force is dispersion force.
- It is present between symmetric atoms or non-polar molecules, e.g., $H_2, Cl_2, P_4, CH_4, CCl_4, C_6H_6$.
- These are always attractive in nature.
- The interaction energy is inversely proportional to the sixth power of the distance between two interacting particles, i.e., $E \propto 1/r^6$, where $r$ is the distance between two particles.
- These forces are significant only at short distances $(\sim 500 \ pm)$ and their magnitude depends on the polarisability of the particle.