Check your understanding

Exercise 1. Answer the following questions.

1. What is the most widely used optical device?

   1. The most widely used optical device is a telescope.

   2. The most widely used optical device is a prism.

   3. The most widely used optical devise is a microscope.

   4. The most widely used optical devise is a lens.

2. Which definition of the lens is correct?

   1. An optical system consisting of two or more refracting interfaces, at least one of which is curved.

   2. Nonplanar surface centered on a common axis.

   3. Two spherical segments coated with thin dielectric films.

   4. Optical system used for converging or diverging of light waves.

3. Which of these natural objects can we use as a lens?

   1. Our eyes

   2. A droplet of water

   3. Lake surface

   4. A pearl