Now let us look at part two of light microscopy. In this part two will focus on concepts related to microscopy, namely magnification, resolution, power and index of refraction. We will also look at the other configurations for light microscopy apart from bright field, those are the phase contrast, the dark field and the fluorescent microscopes. Some of the main concepts related to microscopy are magnification the increase in the apparent size of the specimen observed resolution power transmits light without variation and allows closely spaced objects to be clearly distinguished as two separate objects. index of refraction the measure of the light Ending ability of a medium. Let us examine each one of these closely.

Magnification of the image of a specimen is accomplished by objective and ocular lenses. The multiplication shot sign is shown as x. Four times. objective lens usually has three powers, a 10 x known as low power 40 x known as high power and hundred x Nunez oil immersion lens. The ocular lens has only a 10 x magnification. So the total magnification is given by multiplying the power of the objective lens by the power of the auction lens.

So suppose the objective lens is 40 X and the ocular lens is 10 x Of course, then the total magnification is 400 X. As a reminder, the image that the objective lens magnifies and inverts is an intermediate image. The ocular lens then magnifies even further, the already magnified inverted image as the final image that we see under the scope. Resolution allows us to see two objects as separate from one another. An example of resolution is a car seen in the distance at night seemed to have one headlight because of lack of resolving power in an unaided eye. However, if we use binoculars we will be able to see the two headlights of the car due to the increase resolving power.

Have the binoculars with our oil immersion lens is the highest resolution possible with light microscope is point one seven micro meters or 170 nanometers, that too with the help of 100 x oil immersion objective lens, the human eye has there is a resolution capacity of only 100 micro meters. When switching from the 10 X or the 40 X to oil emotion, the image becomes fuzzy the objects lacks resolution and the resolution power appears to be poor. The poor resolving power results from the poor refraction of light which we will look into next Fine object to be seen distinctly the lens system must have a good resolving power. It is the power to transmit light without variation and allow closely placed objects to be seen as separate. Shown here is the cell division during anaphase. In onion selves, the dry image on the right lacks clarity of the chromosomes.

The image with oil allows for us to distinguish each chromosome and be able to see them theory. Now, let us look at index of refraction. It is the light bending ability of a medium such as glass or oil. For glass the index of refraction is one. For oil the index of refraction is 1.5, which is very close to that of glass. Both the 10 X and the 40 s objectives are wide enough to capture sufficient light for viewing.

The oil immersion objective however, is relatively so narrow that most of the light went away and misses the objective lens without the presence of oil that is in the presence of air. The index of refraction of oil is 1.5 which is almost identical to that of the index of reflection refraction of less. So, by immersing the lens oil the light does not bend away, as shown here by the blue arrow does not bend away from the lens as it passes through the glass and the specimen all y'all does probably winds, a homogeneous pathway for light from the slide to the objective and the resolution power therefore increases as mentioned before. light microscope has other configurations apart from brightfield and those are the phase contrast, dark field and fluorescent microscopy. In light microscope staining of the cells is needed and cells usually die in the process of heat fixation.

Shown here is a picture of paramecium in all three configurations. In France, contrast microscopy living unstained organisms can be viewed. That is because of a special condenser on objective lenses. that are used in dark field microscopy. As the name suggests, there is a darker background and it provides a good resolution. The last type of configuration to consider is fluorescent microscopy.

In this fluorescent dyes such as floor sign, which is green in color, or Roman, which is red in color are used to tag certain parts of the cell, let it be the cell membrane protein, or DNA or underscore protein, each with a different color to provide contrast. The dyes are then eliminated by UV, our ultra violet light shown here is an example of cells speculating from Bacillus subtilis. And you can see then the spores in Green science summary magnification increases the apparent size of the specimen. This is accomplished by the use of ocular and objective lenses. Resolution power allows for two closely spaced objects to be seen as distinct, this is done by using oil. If index of refraction is the measure of light bending ability of a medium, this is also accomplished by using oil as a medium.

And there are other configurations apart from brightfield those are the phase contrast in which one can see living unstained cells, dark field microscopy, which provides a dark background and therefore a good resolution and fluorescent microscopes for which the specimens are coated with fluorescent dyes and I UV source of light is used to eliminate the specimen. This concludes our study of light microscopy.