ANS:D - both (b) & (c)

The poise (P) is a unit of dynamic viscosity in the CGS (centimeter-gram-second) system of units. It is named after Jean Louis Marie Poiseuille, a French physician and physiologist known for his work on fluid dynamics. The poise is defined as the dynamic viscosity of a fluid with a shear stress of 1 dyne per square centimeter (dyn/cm²) and a shear rate of 1 reciprocal second (1/s or s^-1) between two parallel layers of the fluid, separated by a distance of 1 centimeter (cm). Mathematically, it can be expressed as: 1 poise=1 gm/cm sec1poise=1gm/cm sec This means that if you apply a shear stress of 1 dyne/cm² to a fluid, and the fluid layers move relative to each other at a rate of 1 cm/s over a distance of 1 cm, then the dynamic viscosity of the fluid is 1 poise. For example, water at 20°C has a dynamic viscosity of approximately 0.01 poise or 1 centipoise (cP). This means that to maintain a shear rate of 1/s in water, you would need to apply a shear stress of 0.01 dyne/cm². In summary, the poise is a unit used to quantify the resistance of a fluid to flow under an applied force, with higher values indicating higher viscosity.