brodidit for students
Optical instruments
Class 11 · Physics · 5 questions
Name: ____________________ Date: ____________
The magnifying power of a simple microscope for a near point of 25 cm and focal length 5 cm is (image at the near point):
- A 5
- B 25
- C 30
- D 6
A telescope's magnifying power (normal adjustment) is:
- A f objective x f eyepiece
- B f objective - f eyepiece
- C f eyepiece / f objective
- D f objective / f eyepiece
The human eye forms its image on the:
- A Cornea
- B Pupil
- C Retina
- D Iris
Short sight is corrected with a:
- A Concave lens
- B Plane mirror
- C Convex lens
- D Prism
In an optical fibre, light travels by:
- A Diffraction
- B Refraction only
- C Total internal reflection
- D Dispersion
Answer key
1. D, 2. D, 3. C, 4. A, 5. C
M = 1 + D / f = 1 + 25 / 5 = 6.
M = f_o / f_e.
The retina holds the light sensitive cells.
A diverging lens moves the image back onto the retina.
Light is trapped in the core by total internal reflection.