Explain the observations when a thistle funnel is moved deeper into water and then replaced with glycerine.

Here are the observations and explanations:

a) When the thistle funnel is moved downwards:
The difference in the liquid levels in arms A and B of the U-tube manometer increases.
This is because liquid pressure increases with depth. As the funnel goes deeper, the pressure exerted on its membrane increases, pushing the liquid in the manometer further.

b) If the depth remains the same and water is replaced with glycerine:
The difference in the liquid levels in arms A and B of the U-tube manometer increases compared to when water was used.
This is because glycerine is denser than water. Liquid pressure is directly proportional to the density of the liquid ($P = \rho gh$). A denser liquid at the same depth will exert greater pressure.