Ans. The relationship between pressure and depth in a fluid is described by Pascal's law. According to this law, the pressure exerted by a fluid increases with depth. This is because the weight of the fluid above a certain point causes an increase in pressure at that point. The relationship can be mathematically expressed as P = ρgh, where P is the pressure, ρ is the density of the fluid, g is the acceleration due to gravity, and h is the depth of the fluid.