Question

1) On the compound microscope, what is the function of the condenser? (a) to control the amount of light that reaches the object, (b) to control the intensity of light that reaches the object, (c) to focus light onto the object, (d) to reduce the amount of light that reaches the object, (e) to block light in the center of the light cone

2) Why is it important to use lens paper when cleaning your microscope? (a) Kim-Wipes work better than lens paper, (b) paper towels are better at absorbing oil, (c) Ordinary paper will produce a better shine on the lens, (d) Lens paper is less likely to scratch the lens, (e) Kim-Wipes produce less lint

3) Which of the following statements is false? (a) Your attire must constitute minimum reasonable coverage from head to toe. (b) Gloves that have contacted no harmful agents can be discarded into the regular trash (c) never leave an open flame unattended, (d) Any work that you submit must be the product of your efforts only, (e) slides should be disposed of in the glass-waste container

4) What happens to area of the field of view when you increase the objective magnification from 4X to 40X? (a) increases by a factor of 100, (b) decreases by a factor of 100, (c) increases by a factor of 10, (d) decreases by a factor of 10, (e) increases by a factor of 400

5) Of what use is staining yeast with LPCB? (a) rapid and inexpensive way to detect fungal infections in people, (b) cotton blue will preferentially bind to fungal cell walls, (c) ensure that cells are dead before they are fixed with lactate, (d) produces higher-resolution images with a 10X objective lens than with a 40X lens, (e) contrast increase in value

Answer 1

Ans 1. The function of condenser in the microscope :

Correct option (c) to focus light onto the object

Explanation: It is an optical lens that is fitted below the stage. It gathers the light from the illuminator and focuses it on the specimen thus used in getting a clear and magnified image of the object.

Incorrect options:

(a) to control the amount of light that reaches the object

Explanation: Diaphragm, that is present under the stage and above the condenser controls the amount of light that reaches the object. Generally, two types of the diaphragm are available for use in a microscope.

Disc diaphragm: It's a rotating disc that has 5-10 holes of various sizes. By selecting appropriate hole we can control the amount of light that reaches the object. This diaphragm is less expensive and simple in working.

Iris diaphragm: It has a hole whose diameter can be adjusted. Its function resembles the iris of the human eye or the camera shutter.

(b) to control the intensity of light that reaches the object

Explanation: It is again the function of the diaphragm it can be done by selecting the proper hole (disc diaphragm) or adjusting diameter (iris diaphragm).

(d) to reduce the amount of light that reaches the object.

Explanation: This is done by the diaphragm. In disc diaphragm, this is done by selecting a smaller hole thus reducing the amount of light that reaches the object. In iris diaphragm, this is done by reducing the diameter of the aperture.

(e) to block light in the center of the light cone

Explanation: This concept is used in the dark field microscope. The light in the center of the light cone is blocked by placing the opaque disc below the condenser. By doing this light is allowed to pass only through the object and not from the surrounding. So the object appears bright on the dark background hence it is called dark field microscope.