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Which of the following objectives should you never use the coarse focus knob with?

Which of the following objectives should you never use the coarse focus knob with?

The coarse adjustment knob is used ONLY with the low power (4X, 10X) objectives. When focusing under the 40X or 100X objective, ONLY use the fine adjustment, never the coarse adjustment.

Why do 100x objectives need oil?

However, once you use the 100x objective lens, the light refraction when using a dry lens is noticeable. By placing a substance such as immersion oil with a refractive index equal to that of the glass slide in the space filled with air, more light is directed through the objective and a clearer image is observed.

Why do we use oil in oil immersion?

In light microscopy, oil immersion is a technique used to increase the resolving power of a microscope. This is achieved by immersing both the objective lens and the specimen in a transparent oil of high refractive index, thereby increasing the numerical aperture of the objective lens.

What is the purpose of immersion oil?

Immersion oil increases the resolving power of the microscope by replacing the air gap between the immersion objective lens and cover glass with a high refractive index medium and reducing light refraction.

Do you use a coverslip with oil immersion?

Oil-immersion objectives should be used with coverslip-thick glass (or optically equivalent plastic) to achieve their best imaging performance. This can be easily done by turning the glass slide over and viewing the cells through the 1-mm thick slide, with the coverslip facing away from the objective.

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How much does oil immersion magnify?

The oil immersion objective lens provides the most powerful magnification, with a whopping magnification total of 1000x when combined with a 10x eyepiece.

What is the best way to clean immersion oil from the microscope lens?

6 Tips to Properly Clean Immersion Oil off Your Objectives

  1. Clean off the oil immediately after using it.
  2. Use the eyepiece to inspect any dust on the objective.
  3. Remove any dust or dirt with a blower.
  4. Fold a piece of lens paper to create a point.
  5. Soak the lens paper in a suitable solvent.
  6. Wipe from the center to the outside in a spiral pattern.

What is the safest solvent for cleaning an objective lens?

Acetone is the safest solvent for cleaning an objective lens. Only lint-free, optically safe tissue should be used to wipe off microscope lens. The course focus knob can be used to adjust the focus when using any of the objective lenses.

What to use to clean the lens of a microscope?

Remove oily dirt using either a lens cleaning fluid or absolute ethanol on a cotton swab or lens tissue. Stubborn contamination may require several passes, or a stronger solvent such as methanol or acetone. 7. Discard the cotton swab or lens tissue after every use.

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What are some precautions for working with the oil immersion lens?

A wet mount must be very secure to use oil. Oil immersion lenses are used only with oil, and oil can’t be used with dry lenses, such as your 400x lens. Lenses of high magnification must be brought very close to the specimen to focus and the focal plane is very shallow, so focusing can be difficult.