Compound Microscope

Q.

The focal length of the objective lens of a compound microscope is [CPMT 1985; MNR 1986; M

1. Equal to the focal length of its eye piece

2. Less than the focal length of eye piece

3. Greater than the focal length of eye piece

4. Any of the above three

Q.

What will the value of angular magnification be if the final image is formed at near point, instead of infinity?

1. $m=\left(\frac{L}{f_O}\right)(1+D/f_e)$

2. $m=\left(\frac{L}{f_e}\right)(1+D/f_O)$

3. $m=\frac{L}{f_O}$

4. $m=\frac{LD}{f_O{f}_e}$

Q. A compound microscope has a magnifying power 30. The focal length of its eye-piece is 5 cm. Assuming the final image to be at the least distance of distinct vision. The magnification produced by the objective will be

1. 5
2. -5
3. 6
4. -6

Q.

How should people wearing spectacles work with a microscope

1. They cannot use the microscope at all

2. They should take off spectacles

3. They should keep on wearing their spectacles

4. (b) and (c) is both way

Q.

The magnifying power of a microscope with an objective of 5 mm focal length is 400. The length of its tube is 20 cm. Then the focal length of the eye-piece is [MP PMT 1991]

1. 200 cm

2. 2.5 cm

3. 160 cm

4. 0.1 cm

Q.

Microscope is an optical instrument which

1. Enlarges the object

2. Increases the visual angle formed by the object at the eye

3. Decreases the visual angle formed by the object at the eye

4. Brings the object nearer

Q.

When the length of a microscope tube increases, its magnifying power [MNR 1986]

1. Increases

2. Does not change

3. May decrease or increase
4. Decreases

Q.

In a compound microscope, if the objective produces an image $I_o$ and the eye piece produces an image $I_e$, then

1. I_o is virtual but I_e is real

2. I_o is real but I_e is virtual

3. I_o and I_e are both virtual

4. I_o and I_e are both real

Q. In a compound microscope, the focal length of the objective and the eye lens are 2.5 cm and 5 cm respectively. An object is placed at 3.75 cm before the objective and image is formed at the least distance of distinct vision, then the distance between two lenses will be (i.e. length of the microscopic tube)

1. 12.67 cm
2. 13.00 cm
3. 12.00 cm
4. 11.67 cm

Q. The magnifying power of a microscope with an objective of 5 mm focal length is 400. The length of its tube is 20 cm. Then the focal length of the eye-piece is (consider that final image is formed at infinity)

1. 160 cm
2. 2.5 cm
3. 0.1 cm
4. 200 cm