Ray Optics and Optical Instruments

Topics in this chapter

• Spherical Mirrors and Images
• Refraction, Slabs and TIR
• Lenses and Lens Combinations
• Prisms and Deviation
• Optical Instruments and Magnification
• Polarization and Malus’ Law

Cheat sheet

Practice questions

1. Question 1Q-6D8744

   A point object is placed at a distance of 30 cm from a convex mirror of focal length 30 cm. The image is formed at:

   1. A.Infinity
   2. B.15 cm behind the mirror
   3. C.15 cm in front of the mirror
   4. D.30 cm behind the mirror
   See the answer and solution
2. Question 2Q-1C0389

   A ray of light is incident at an angle of incidence $i$ on one face of a prism of small refracting angle $A$ and refractive index $\mu$. The deviation $\delta$ produced by the prism is independent of $i$ and is given by:

   1. A.(\mu - 1)A
   2. B.(\mu + 1)A
   3. C.(\mu - 1)/A
   4. D.\mu A
   See the answer and solution
3. Question 3Q-868451

   A convex lens of focal length 20 cm is made of glass of refractive index 1.5. When it is immersed in a liquid of refractive index 1.33, its focal length becomes approximately:

   1. A.20 cm
   2. B.40 cm
   3. C.78 cm
   4. D.10 cm
   See the answer and solution
4. Question 4Q-7DB368

   The critical angle for a medium is $30^\circ$. The speed of light in this medium is:

   1. A.$1.5 \times 10^8\text{ m/s}$
   2. B.$3 \times 10^8\text{ m/s}$
   3. C.$2 \times 10^8\text{ m/s}$
   4. D.$1 \times 10^8\text{ m/s}$
   See the answer and solution
5. Question 5Q-FE60ED

   An astronomical telescope has an objective of focal length 100 cm and an eyepiece of focal length 5 cm. If the final image is formed at infinity, the magnifying power and length of the telescope tube respectively are:

   1. A.-20, 105 cm
   2. B.-20, 95 cm
   3. C.-5, 105 cm
   4. D.-100, 100 cm
   See the answer and solution