Deeper questions

The following questions require some thought and reaching the answer may require you to think beyond the contents of this TLP.

1. How should the initial focusing of the microscope be done?

   a	With the coarse focus moving the lens towards the specimen.
   b	With the fine focus moving the lens towards the specimen.
   c	With the coarse focus moving the lens away from the specimen.
   d	With the fine focus moving the lens away from the specimen.

    Answer

2. The specimen preparation is important in metallurgy because:

   a	A poorly prepared specimen can damage the microscope.
   b	A poorly prepared specimen will distract from features on the specimen.
   c	Only a well prepared specimen will reflect light.
   d	A poorly prepared specimen will corrode, and the resulting images will be misleading.

    Answer

3. When increasing the magnification on the microscope, which of the following occurs?

   a	The depth of field increases.
   b	The resolution limit decreases.
   c	The visible area decreases.
   d	The contrast increases.

     Answer

4. When the aperture stop is made smaller, which of the following occur?

   Yes	No	a	The depth of field increases.
   Yes	No	b	The resolution decreases.
   Yes	No	c	The contrast increases.
   Yes	No	d	The brightness increases.

     Answer

5. The red tint plate (also known as a full wave sensitive tint plate) increases the contrast in a polarised light microscope because:

   a	Our eyes are more sensitive to red light, so it is easier to see the light and dark areas when there is a red tint plate.
   b	The red tint plate only lets a small window of wavelengths through, and so increases the birefringence.
   c	The red tint plate displaces the ordinary and the extraordinary beams by an extra wavelength, so that small differences in birefringence cause large differences in colour.
   d	The red tint plate increases the differences in birefringence in the material so that the different grain directions cause a greater difference in colour than in just the polarised light.

     Answer

6. Contrast in reflected microscopy tends to be caused by:

   a	Variations in topography and differences in reflectivity of areas.
   b	Only differences in reflectivity of areas.
   c	Only topography.
   d	Variations in thickness of the specimen.

    Answer

7. If a graticule is observed under the 10x lens of a microscope so that the diameter of the field of view is from 150 µm to 450 µm on the graticule, what is the width of one lamella when it takes 15 lamellae to fill the field of view when viewed under the 50x lens.

         Answer