Simple Microscope

Q. Which of the following optical instrument is used for watch repair and testing of precious gems?

1. Compound microscope
2. Simple microscope
3. Reflecting telescope
4. Refracting telescope

Q. The magnifying power of a simple microscope can be increased, if we use eye-piece of

1. Higher focal length

2. Smaller focal length

3. Higher diameter

4. Smaller diameter

Q. The magnifying power of a simple microscope when the final image is formed at $D=25\text{cm}$ from eye is :
($f$ is the focal length)

1. $1+\frac{D}{f}$
2. $1-\frac{D}{f}$
3. $1+\frac{f}{D}$
4. $\frac{D}{f}$

Q. Which of the following optical instruments is used in repairing watches and testing precious gems?

1. Reflecting telescope
2. Simple microscope
3. Compound microscope
4. Refracting telescope

Q. A simple microscope has a magnifying power of 3.0 when the image in formed at the near point (25 cm) of a normal eye. What is its focal length?

Q. Objects which cannot be seen by naked eyes are observed through a ______.

1. microscope
2. telescope
3. glass
4. (b) and (c) above.