What converts for curvature in a field so that a flat field with ...

[OSWALD]

What converts for curvature in a field so that a flat field with uniform focus is seen?
 
  a. Achromatic objective lens
  b. Plan-achromatic objective lens
  c. Spherical correction ocular lens
  d. Blue filter when placed above the condenser

Question 2

An image viewed under the microscope is clearly seen under both the 10 and 40 objectives, but it is not visible under 100. What is the most likely reason for this?
 
  a. Oil is too thick on the slide.
  b. The slide is placed upside down on the stage.
  c. The slide has a coverslip on it.
  d. No oil is on the slide.

[succesfull]

Answer to Question 1

ANS: B
A plan-achromatic objective lens, though more expensive, provides a flat field so that uniform focus is seen across a slide. An achromatic objective lens does not correct for the curvature in a round field, and the edges of the field appear fuzzy or out of focus when the center is in focus. No such thing as a spherical ocular lens exists; a blue filter eliminates the yellow emitted by a tungsten-halogen light bulb.

Answer to Question 2

ANS: B
When an image is clearly visible under both 10 and 40 objective lenses but nothing is seen under oil immersion, even with oil on the slide, the slide is most likely upside down on the stage. The clinician should clean the oil off the wrong slide and turn the slide over, placing oil on the top side.

[OSWALD]

Gracias!

[AngeliqueG]

Thanks for the timely response, appreciate it