Question

Assertion (A): Darc's law is valid for a steady and stationary flow process in the soil.
Reason (R): In a steady flow condition, potential and gradient at every point in the flow path remain constant.

• A. Both (A) and (R) are correct and (R) is the correct explanation of (A)
• B. Both (A) and (R) are correct but (R) is NOT the correct explanation of (A)
• C. (A) is correct but (R) is not correct
• D. (A) is not correct but (R) is correct

Hint:

Darc’s law is valid under steady-state, laminar flow in porous media.

Answer 1

The Correct Option is A

Step 1: Darcy's law, \( q = -K \dfrac{dh}{dl} \), assumes the hydraulic gradient stays constant with time.
Step 2: This constant-gradient condition only holds true under steady, stationary flow.
Step 3: If flow were unsteady, potential at each point would change with time, breaking the assumption behind the law.
Step 4: Correct option, both (A) and (R) are correct and (R) is the correct explanation of (A).