Class 11th| Botany ViVa -Voce Question Answers
Ans. A microscope is an instrument used to magnify small objects and thus increases the resolution.
Q.2. What is the function of a microscope?
Ans. Its function is to enlarge near or small objects.
Q.3. What type of microscopes are generally used in the school laboratory ?
Ans. ) Dissecting microscope and (ii) Compound microscope.
Q.4. Define resolving power.
Ans. Resolving power may be defines as the ability to distinguish two objects as separate entities.
Q.5. What is the role of mirror in a compound microscope ?
Ans. To reflect the light on the object so as to illuminate it.
Q.6. What is the function of a diaphragm in a microscope ?
Ans. It regulates the light falling on the object.
Q.7. What type of image do you see by the microscope real or virtual ?
Ans. Real image.
Q.8. What do you mean by working distance in a microscope ?
Ans. This is the distance between the objective lens and the specimen being observed, and it decreases
when you move from low to high power.
Q.9. Which lens, objective or eye-piece, has a smaller focal length in a compound micro-
scope ?
Ans. Objective lens.
Q. 10. You are given two convex lenses of focal length 5 cm and 25 cm. Which one will you
Ans. Objective lens.
choose as objective lens for forming a compound microscope ?
Ans. Convex lens of focal length 5 cm.
Q. 11. Why is compound microscope both the objective and the eye-piece are of small focal
lengths ?
Ans. To increase the magnifying power.
Q.12 Why do we prefer a magnifying glass of smaller focal length ?
Ans. M= (1 + D/f). Therefore, M will be large, if f is small.
Q. 13. Name various other types of microscopes.
Ans. ) Fluorescent microscope, (ii) Phase contrast microscope, (iii) UV microscope (iv) Polarising
microscope, (u) Interference microscope, etc.
Q. 15. What is an electron microscope ?
Ans. An electron microscope is a device used to study the ultra structure of cell Organells etc etc. A stream of high electron is used for magnification in an electron microscope.
Q16. How many times does an electron microscope raagnify ?
Ans. 1,00,000 times.
Q.17. Who invented electron microscope ?
Ans. Knoll and Ruska in 1932
Q. 18. Define microscopy.
Ans. The use of microscopes to study the cells is called microscopy.
Q.19. Name the type of microscope used by Robert Hooke.
Ans. Simple Microscope.
Q.20. What is magnification ?
Ans.Maginification = Size of retinal image with i instrument
_________________________________
Size of retinal image with unaided
normal eye .
Q.21. How is an image formed in a compound
microscope '?
Ans. The objective lens produces in initial image of the object which is magnified by the ocular lens
and the final real image is formed.
Q. 22. Why is it advised to always use coverslip over the slide?
Ans. Coverslip keeps the slide dry otherwise glycerine or stain can spoil the objective.
Q.23. What is the role of condenser in a microscope ?
Ans. Condenser regulates the amount of light falling on the object over the slide
Q.24. State the factors on which the resolving power of a microscopic depends.
Ans. Resolving power depends upon the wavelength and the numerical aperture of the objectve lens.
Q.25. Under compound microscope, fixed, killed cells are studied. How are living cells
studied ?
Ans. To study iving cells, phase contrast and interterence microscope are used. Various cell organelles have different thickness and refractive index which cause a phase difference and contrast. This increases the visibility.
Q.26. Why is a concave surface of the mirror used to direct light for high power objective
lens ?
Ans. High power needs more light at one point so concave mirror converges the light rays at the
object.
{Chapter 1
Study of Different Parts of a Compound Microscope.}
[Chapter 2
Coming Soon]
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