# Bright field microscope Objective Question

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1. Why ordinary microscope is called bright field microscope?

• a) It forms a brighter image against dark background
• b) It forms a darker image against bright background
• c) It forms a brighter image in bright background
• d) It forms a darker image in dark background

2. Which one of the following is a part of bright field microscope?

• a) Arm
• b) Diaphragm
• c) Light source
• d) All of the above

3. What is the function of condenser?

• a) To create illumination
• b) To move stage
• c) To focus a cone of light on slide
• d) All of the above

4. The image should remain in focus when objective lenses are changed. This property of microscope is known as:

• a) Magnification
• b) Resolution
• c) Parfocal
• d) None of the above

5. The lens nearer to eye, when viewing in microscope is known as:

• a) Nose piece
• b) Ocular lens
• c) Objective lens
• d) Oil immersion lens

6. Minimal resolvable distance between two objects is equal to:

• a) 0.5ƛ/ɳ sin ɵ
• b) 0.5ƛ/ɳ cos ɵ
• c) 0.05ƛ/ɳ sin ɵ
• d) 0.05ƛ/ɳ cos ɵ

7. What is the approximate focal length for scanning objective?

• a) 20mm
• b) 40mm
• c) 10mm
• d) 4mm

8. What should be the working distance for high power objective?

• a) 0.5-0.7mm
• b) 0.7-0.9mm
• c) 0.9-1.0 mm
• d) 1.0-1.2 mm

9. The resolving power is limited by the __ of the illuminating beam.

• a) Frequency
• b) Velocity
• c) Speed
• d) Wavelength

10. What is the numerical aperture of low power objective?

• a) 0.65
• b) 0.25
• c) 1.25
• d) 0.10

11. To focus a specimen, it is best to start with which objective?

• a) High power
• b) Low power
• c) Scanning
• d) Oil immersion

12. For which of the following specimens would you use a dissecting scope?

• a) Human skin cells
• b) Insect mouth parts
• c) Escherichia coli
• d) Newspaper print.

13. Which objective provides the greatest field to view?

• a) This depends on if the specimen is stained
• b) Low power
• c) High power
• d) Oil immersion

14. Which one can act as a source of illumination for microscopes?

• a) Ultraviolet light
• b) Sunlight
• c) Visible light
• d) All of the above

15. Which equation represents resolution of an entire microscope?

• a) d/NAobjective + NAcondenser
• b) ƛ/NAobjective x NAcondenser
• c) ƛ/NAobjective + NAcondenser
• d) d/NAobjective x NAcondenser

16. What would be the resolving power of microscope with low power objective (NA 0.25) and 530 nm light wavelength?

• a) 212nm
• b) 1060nm
• c) 2120nm
• d) 4240nm

17. What would be the resolving power of microscope with high power objective (NA 0.65) and 550 nm light wavelength?

• a) 212nm
• b) 846nm
• c) 423nm
• d) 1692nm

18. Identify correct match of magnification, numerical aperture, focal length, working distance
criteria shown in below columns:

• a) 1 and ii), 2 and iv), 3 and i), 4 and iii)
• b) 1 and ii), 2 and iii), 3 and iv), 4 and i)
• c) 1 and iii), 2 and i), 3 and ii), 4 and iv)
• d) 1 and iv), 2 and iii), 3 and ii), 4 and i)

19. What do you mean by binocular microscope?

• a) Contains 2 eyepieces
• b) Contains only 2 objectives
• c) Contains at least 2 objectives
• d) Contains 2 lenses in eyepiece

20. Which microscope can be used to view living microbes?

• a) Bright field microscope
• b) Fluorescence microscope
• c) Phase contrast microscope
• d) All of the above

21. One micrometer is equal to:

• a) 10-6 meter
• b) 10-3 meter
• c) 10-9 meter
• d) 10-10 meter

22. What does binocular microscope contain?

• a) Two oculars
• b) Two objectives
• c) One objective & one eye piece
• d) Two oil immersion lenses

23. Which one of the following is exact definition of parfocal?

• a) The image would be focused by fine adjustment
• b) The image would be focused by coarse adjustment
• c) Image should remain in focus, when objectives are changed
• d) Image should remain in focus, when oculars are changed

24. The image what we observe in microscope is created by:

• a) Objective
• b) Ocular
• c) Both a & b
• d) Either of a or b

25. How will you calculate total magnification of image?

• a) By making total of magnification of objective &eyepiece
• b) By making multiplication of magnification of objective &eyepiece
• c) By total of magnification of all objectives attached to nose piece
• d) By multiplication of magnification of all objectives attached to nose piece

26. If microscope contains 45x objective &5x eyepiece, the total magnification will be:

• a) 450x
• b) 225x
• c) 125x
• d) 50x

27. Which one of the following is exact definition of resolution?

• a) The ability of a lens to separate or distinguish between small objects those are far from each other
• b) The ability of a lens to separate or distinguish between small objects those are close together
• c) The ability of a lens to separate or distinguish between small objects that are overlapping each other
• d) None of the above

28. To obtain greatest possible resolution in bright field microscope one can use light with
wavelength:

• a) 450-500nm
• b) 500-550nm
• c) 550-600nm
• d) 700-800nm

29. The refractive index of air is:

• a) 0.1
• b) 1
• c) 10
• d) None of the above

30. The refractive index of glass &cedar wood oil is:

• b) Differ about 0.5 from each other
• c) Nearer to each other
• d) 10 times higher than air

31. The refractive index of glass & cedar wood oil is:

• a) About 1.5 times higher than air
• b) Nearer to each other
• c) Average 1.53
• d) All of the above

32. The lens working in an air cannot have numerical aperture more than:

• a) 1.25
• b) 1.00
• c) 0.65
• d) 0.25

33. How can we increase numerical aperture more than 1?

• a) By using air
• b) By using immersion oil
• c) Both a & b
• d) None of the above

34. Which of the following are true magnification, numerical aperture, focal length & working
distance of criteria for an oil immersion lens?

• a) 45X, 0.65, 4mm, 0.7mm
• b) 100X, 1.25, 1.8mm, 0.1mm
• c) 100X, 0.25, 16mm, 8mm
• d) 4X, 0.10, 40mm, 20mm

35. Which of the following are true magnification, numerical aperture, focal length & working
distance of criteria for high power objective?

• a) 45X, 0.65, 4mm, 0.7mm
• b) 100X, 1.25, 1.8mm, 0.3mm
• c) 100X, 0.65, 16mm, 8mm
• d) 4X, 0.10, 60mm, 20mm

36. Which of the following are true magnification, numerical aperture, focal length & working
distance of criteria for low power objective?

• a) 45X, 0.25, 16mm, 0.7mm
• b) 100X, 1.25, 3.8mm, 0.1mm
• c) 10X, 0.25, 16mm, 8mm
• d) 4X, 0.10, 40mm, 30mm

37. In ɳsinɵ equation of numerical aperture, ɵ is:

• a) The angle of the cone of light entering in an objective
• b) 1/2angle of the cone of light entering in an objective
• c) 1/4 angle of the cone of light entering in an objective
• d) None of the above

38. In ɳsinɵ equation maximum value of ɵ is:

• a) 90°
• b) 45°
• c) 180°
• d) 360°

39. The maximum value of sinɵ is:

• a) 0.5
• b) 0.65
• c) 1.00
• d) 1.25

40. The working distance can be defined as the distance between:

• a) Objective &eyepiece
• b) 2 objectives
• c) Objective &condenser
• d) Objective &specimen on slide

41. Which of the following objective works on shortest working distance?

• a) Low power
• b) Scanning lens
• c) Oil immersion lens
• d) High power

42. The objective with large working distance will have:

• a) Small numerical aperture &low resolving power
• b) Large numerical aperture &high resolving power
• c) Large numerical aperture &low resolving power
• d) Small numerical aperture &high resolving power

43. The resolution of microscope depends on:

• a) Numerical aperture of objective
• b) Numerical aperture of condenser
• c) Wavelength of light
• d) All of the above

44. Microscope condenser contains numerical aperture about:

• a) 1.0
• b) 1.3
• c) 1.5
• d) 2.0

45. The maximum obtainable theoretical resolution of light microscope with oil immersion lens is:

• a) 212nm
• b) 312nm
• c) 112nm
• d) 252nm

46. What is the maximum obtainable theoretical resolution of light microscope with oil immersion lens?

• a) 0.2μm
• b) 0.3μm
• c) 0.02μm
• d) 0.03μm

47. A light microscope can maximum distinguishes between 2 dots about __μm apart:

• a) 0.3μm
• b) 0.2μm
• c) 0.1μm
• d) 0.4μm

48. can prepare bright field microscope with even 10,000X magnification, but it is not useful
because:

• a) It is costlier
• b) It would simply magnify blur
• c) Increase the amount of artifacts
• d) All of the above