# Immersion objectives Question

## Important Question

1. What is the possible angle of largest cone of light (come from object) which can be obtained
using high power objective?

• a) 62°
• b) 134°
• c) 82°
• d) 150°

2. What is the refractive index of water, air and cedarwood oil respectively?

• a) 1.0, 1.33, 1.51
• b) 1.51, 1.33, 1.0
• c) 1.33, 1.0, 1.51
• d) 1.33, 1.51, 1.0

3. Which of the following is to be used to obtain a cone of light of about 134°?

• a) Air
• b) Water
• c) Cedarwood oil
• d) Any of the above

4. Two lines close together _ can be separated with an oil immersion objective and
numerical aperture of 1.4.

• a) 0.50 µ
• b) 0.25 µ
• c) 2500 nm
• d) None of the above

5. The the NA of the objective, the __ will be its resolving power.

• a) Greater, greater
• b) Smaller, smaller
• c) Greater, smaller
• d) Both a) and b)

6. Which of the following material contain refractive index approximately around 1.52?

• a) Sandalwood oil
• b) Crown oil
• c) Cedarwood oil
• d) All of the above

7. What do you mean by equivalent focus?

• a) Objective lens system produces a real image of the object of the same size as it is produced by a simple biconvex lens
• b) Objective lens system produces a real image of the object of the same size as it is produced by a simple biconvex or converging lens
• c) Objective lens system produces a real image of the object of the same size as it is produced by a converging lens
• d) Objective lens system produces a virtual image of the object of the same size as it is produced by a simple biconvex or converging lens

8. The working distance is always than the equivalent focus of _:

• a) Less, objective
• b) Greater, objective
• c) Less, ocular
• d) Greater, ocular

9. The working distance of objects may be easily determined by:

• a) Knowing the wavelength of light source and multiplying it with numerical aperture
• b) Noting the number of complete turns of the fine adjustment required to bring object in sharp focus
• c) Noting the number of complete turns of the coarse adjustment required to bring object in sharp focus.
• d) All of the above

10. Each turn of micrometer screw (fine adjustment) raise the objective about _:

• a) 1 mm
• b) 0.1 mm
• c) 10 mm
• d) 6 mm

11. If the object is covered with a cover sleep, the working distance will __:

• a) Increase
• b) Decrease
• c) Will not change
• d) None of the above

12. What is correct for cover slip placed on object present on the glass slide?

• a) If cover slip is thicker than working distance of the objective, it will not become possible to get object in focus
• b) If the cover slip is thin, it will be possible to get the object in focus
• c) Focus of the microscope of the object covered with cover glass will be different from that of the uncovered object
• d) All of the above

13. The the refraction of the covering body (cover slip), the __ will be the apparent elevation:

• a) Greater, more
• b) Greater, less
• c) Lesser, more
• d) None of the above

14. How will you calculate the apparent depth of the object below the surface of cover glass?

• a) Index of refraction of cover glass
• b) Reciprocal of index of cover glass
• c) Index of refraction of cover glass multiplied by light wavelength
• d) Total turns of micrometer screw to bring object in sharp focus