What do the numbers on a microscope objective mean?
Microscope objective lenses will often have four numbers engraved on the barrel in a 2×2 array. The upper left number is the magnification factor of the objective. For example, 4x, 10x, 40x, and 100x. The upper right number is the numerical aperture of the objective. For example 0.1, 0.25, 0.65, and 1.25.
What is the magnifying power of compound microscope?
A compound microscope provides a two-dimensional image, while a stereo microscope provides a three-dimensional image. Compound microscopes typically provide magnification in the range of 40x-1000x, while a stereo microscope will provide magnification of 10x-40x.
Why do we use short focal length lenses in compound microscope?
A compound microscope uses a very short focal length objective lens to form a greatly enlarged image. This image is then viewed with a short focal length eyepiece used as a simple magnifier. The image should be formed at infinity to minimize eyestrain.
What is the focal length of objective in compound microscope?
In a compound microscope the focal length of an objective lens is 1.2cm and focal length of eyepiece is 3cm. When the object is kept at 1.25cm in front of the objective, the final image is formed at infinity.
What is the focal length of objective lens of compound microscope?
Depth of focus
| objective focal length (mm) | numerical aperture (N.A.) | maximum useful magnification in compound microscope |
|---|---|---|
| 32 | 0.10 | 100× |
| 16 | 0.25 | 250× |
| 8 | 0.50 | 500× |
| 4 | 0.95 | 1,000× |
What is the focal length of the objective lens?
The focal length of a microscope objective is typically between 2 mm and 40 mm.
How do you measure the focal length of a lens?
Move the lens back and forth until you get a sharp focus. There is a trick to this: place a piece of white paper next to the object so that you can see an image on the paper. The distance from the object to the lens is the focal length. Repeat this measurement five times.
How do you measure the focal length of a concave lens?
You can calculate the focal length (F) of combination of lenses using the formula F = uv/(u+v). The focal length of convex lens (f1) is shown inside the simulator window. You can calculate the focal length of the concave lens using the formula f2 = (f1F/(f1-F).
How do you calculate back focal distance?
The distance from the second lens to the focal point of the combined lenses is called the back focal length (BFL). BFL=f2(d−f1)d−(f1+f2) BFL = f 2 ( d − f 1 ) d − ( f 1 + f 2 ) . As d tends to zero, the value of the BFL tends to the value of f given for thin lenses in contact.