Optics Answers

If you increase the focal length of a telescope's eyepiece with no other changes, then the telescope will have

A. larger total magnification.

B. longer length.

C. the eyepiece with lower optical power.

D. the larger formed image.

The magnification of a simple magnifier is increased when using the magnifier with

A. a shorter focal length.

B. a lower optical power.

C. a higher index of refraction.

D. the larger radius of curvature on both lens surfaces.

A ray of light travels in a block of material and exits to the water (n_w = 1.33). The angle of incidence in the block is 55^o . Select the CORRECT value(s) of an index of refraction for the total internal reflection to occur for the ray in the block.

A. 1.3

B. 1.5

C. 1.7

D. 2.4

Select CORRECT situation(s) when light is undergoing refraction in a medium at a non-zero incident angle.

A. The light changes direction.

B. The speed of light changes.

C. The frequency of the light changes.

D. The wavelength of the light changes.

5. A thin layer of hydrocarbon oil (n₀ = 1.40) is formed on the wet road (n_w = 1.33). Colourful reflections can be seen from the film when illuminated under white light.

(a) A part of the film thickness is 300 nm. Determine the visible wavelength that can be seen on the part.

(b) If the same thickness of kerosene in (a) is spread on a glass (n = 1.5), determine the visible wavelength that can be seen on the part.

Without her contact lenses, Marissa cannot clearly see an object more than 40.0 cm away.

(a) Calculate the focal length of the contact lenses.

(b) What power and type (diverging or converging) of lens should her contact lenses have to give her normal vision?

(c) Suppose Marissa's near point (without her contact lenses) is 15.0 cm. What is the closest object she can see clearly with her contact lenses on?

An object is located 30.0 cm from a passenger's side mirror. The image formed is upright and one third the size of the object.

(a) Is the image real or virtual? Justify your answer.

(b) What is the focal length of the mirror?

(c) Is the mirror concave or convex? Justify your answer.

2. A beam of light strikes one face of a windowpane with an angle of incidence of 30.0°. The index of refraction of the glass is 1.52. The beam travels through the glass and emerges from a parallel face on the opposite side. Ignore reflections.

(a) Calculate the angle of refraction for the ray inside the glass.

(b) Show that the rays in the air on either side of the glass (the incident and emerging rays) are parallel to each other with the aid of a diagram.

(c) Calculate the speed of the light in the glass

1. The bright central fringe in a single-slit diffraction pattern from the blue light of wavelength 476 nm is 2.0 cm wide on a screen that is 1.05 m from the slit.

(a) Without calculating the slit width, determine the width of first-order bright fringe.

(b) How wide is the slit?

(c) If the blue light is replaced with monochromatic red light, what is the effect on the width of the bright central fringe? Briefly justify your answer

A multimode step index fiber has a material dispersion parameter of 250 ps 

nm−1km−l at 1.2 μm. Estimate the pulse broadening for a 10 kilometer long fiber 

with an LED source of spectral width 50 nm.