Question

The value of φ (phi) of a sediment grain having a diameter of 0.125 mm is ______ . (In integer)

Answer 1

Correct Answer: 3

Calculating the ϕ (Phi) Value of a Sediment Grain 

Step 1: Understanding the Formula

The formula to calculate the ϕ (phi) value of a sediment grain is:

\[ ϕ = -\log_2 \left( \frac{D}{1} \right) \]

Where:

• D is the diameter of the grain in millimeters.

Step 2: Substituting the Given Values

Given that the diameter D = 0.125 mm, we substitute this value into the formula:

\[ ϕ = -\log_2 (0.125) \]

Since \( \log_2 (0.125) = -3 \), we get:

\[ ϕ = 3 \]

Final Answer:

Thus, the correct value of ϕ is: 3.