Question

Micrometer instrument is used for measuring which one of the following:

• A. Root pressure
• B. Hydraulic conductivity
• C. Size of micro-organisms
• D. Air humidity

Hint:

In microscopy, the ocular micrometer is calibrated using a stage micrometer to measure cell dimensions in micrometers (\(\mu\text{m}\)).

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Various scientific instruments are utilized in agriculture and biology to quantify environmental parameters or physical dimensions of biological specimens.
Measuring microscopic structures requires optical tools calibrated to very small units of length.

Step 2: Detailed Explanation:
A micrometer (specifically in biological microscopy, consisting of ocular and stage micrometers) is an instrument used to measure the microscopic dimensions (length, width, or diameter) of cells and micro-organisms like bacteria, fungi, and nematodes under a microscope.
Let us evaluate what the other instruments measure:
1. Root pressure: Measured using a Manometer.
2. Hydraulic conductivity: Measured using a Permeameter or through disk infiltrometer techniques in soils.
3. Air humidity: Measured using a Psychrometer or a Hygrometer.
Hence, the micrometer is specifically calibrated for measuring the microscopic sizes of biological entities.

Step 3: Final Answer:
Therefore, the micrometer is used for measuring the size of micro-organisms.