12 Questions
What is the purpose of the ocular micrometer in micrometry?
To provide divisions for measurement
What is the purpose of micrometry?
To measure the size of microscopic organisms
What is the principle underlying micrometry?
Calibration of the ocular micrometer using a stage micrometer
What is the function of the stage micrometer in micrometry?
Used to calibrate the ocular micrometer
In micrometry, what is the value of one small line on the stage micrometer?
$0.01$mm
What is the purpose of calibrating the ocular micrometer?
To determine the number of microns per ocular unit
What should be done to obtain accurate measurements in micrometry?
Aligning the 0-line of ocular and stage micrometers
If the ocular micrometer reads 12 ocular units and the calibration value is 3.5 microns per ocular unit, what is the length of the specimen being measured?
42 microns
What is the formula used to calculate the calibration value of the ocular micrometer?
(Number of ocular units x 1000) / (Number of stage micrometer units)
In the example given, if the ocular micrometer reads 15 ocular units and the stage micrometer is 0.10 mm, what is the calibration value?
6.67 microns/ocular unit
If the calibration value is 4 microns per ocular unit and the specimen measures 28 ocular units, what is the length of the specimen in microns?
112 microns
Which of the following statements about calibrating the ocular micrometer is incorrect?
The calibration value is always expressed in millimeters.
Study Notes
What is Micrometry?
- Micrometry is a technique used to measure the size of microscopic organisms.
- It is based on the principle of calibration of the ocular micrometer using the stage micrometer.
Ocular Micrometer
- The ocular micrometer is a glass disc with 100 equal divisions or lines on it.
- It has no absolute value unless calibrated with the stage micrometer.
- The divisions are counted as "ocular units" until calibrated.
Stage Micrometer
- The stage micrometer is a microscope slide with a standard scale etched into it.
- The smallest divisions are 0.01mm in length, which is equal to 10 microns.
- The value of one small line is 0.01mm, and the value of one big line is 0.10mm.
Calibration of Ocular Micrometer
- To calculate the number of microns per line of the ocular micrometer, divide the number of stage micrometer units by the number of ocular micrometer units, and multiply by 1000.
- Example: 0.05mm divided by 20 ocular units, multiplied by 1000, equals 2.5 microns.
Steps to Perform Micrometry
- Step 1: Place the ocular micrometer in the microscope eyepiece.
- Step 2: Place the stage micrometer on the microscope stage and focus on the scale using LPO.
- Step 3: Adjust the field by moving the stage so that the 0-line on the ocular micrometer is exactly superimposed on the 0-line of the stage micrometer.
- Step 4: Get the stage and ocular measurement by counting the next exact superimposed (big) line on the right from the 0 line.
- Step 5: Calculate the number of microns per line of the ocular micrometer.
- Step 6: Use the calibrated ocular micrometer to measure the size of microscopic organisms.
Learn about Micrometry, a technique used to measure the size of microscopic organisms. Understand the principle of calibrating the ocular micrometer using the stage micrometer. Explore resources like the ocular micrometer, stage micrometer, and microscope slides.
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