Optical Instruments
Optical Instrument Problems
1. A lens with a focal length 4 is used as a simple magnifier. What would be the magnification?
a) When the final image is 25 cm from the eye (the near point)? b) When the final image is at infinity?
2. A astronomical telescope is formed using two lenses, an 90 centimeter focal length lens and a 25 mm focal length lens. a) Which lens is the objective lens? b) Which lens is the eyepiece lens? c) How long is the telescope? d) What is the magnification of the telescope?
3. A galilean telescope is formed using two lenses, a diverging lens with a focal length of 20 mm and a converging lens with a focal length of +12 centimeters. a) Which lens is the objective lens? b) Which lens is the eyepiece lens? c) How long is the telescope? d) What is the magnification of the telescope?
4. An erecting telescope is formed using three lenses, a 80 centimeter focal length objective lens, a 25 centimeter inverting lens, and a 4 centimeter focal length eyepiece lens. a) How long is the telescope? b) What is the magnification of the telescope?
5. A compound microscope is formed using two lenses, a 10 mm focal length lens and a 4 centimeter focal length lens. The two lenses are twenty centimeters apart. a) Which lens is the objective lens? b) Which lens is the eyepiece lens? c) How long is the microscope? d) What is the magnification of the microscope?
6. A philatelist examines a stamp with a converging lens (acting as a simple magnifier) of 10 cm focal length. If the lens is held so that the virtual image is 25 cm from their eye, what is the magnification?
7. The distance between the eyepiece and the objective lens in a compound microscope is 24 cm. The focal length of the eyepiece is 2.0 cm and that of the objective lens is 40 mm. What is the approximate magnification of the microscope?
8. If a Galilean telescope is made using a 20 cm converging lens and a 2.5 cm diverging lens, what will be its magnification? What will be the length of the telescope?
