Optics Answers

Diffraction

A. changes the speed of light.

B. causes a wave to spread in space.

C. changes the wavelength of light.

D. occurs only for monochromatic light.

Coherent sources A and B emit electromagnetic waves with a wavelength of 4 cm. The distance between A and B is 16.0 cm. Point P is located somewhere between A and B. Which of the following values is/are the possible distance of P from A, if it is a point of destructive interference?

A. 7 cm

B. 8 cm

C. 9 cm

D. 11 cm

Which statement(s) is/are TRUE about interference effect by a thin film.

A. The effect cannot occur in a vacuum.

B. The effect depends on the thickness of the film.

C. The effect is due to light reflection on both sides of the film.

D. The effect only occurs when the thin film is illuminated using white light.

Two monochromatic sources are said to be coherent if

A. they have the same frequency.

B. they have the same amplitude.

C. they have constant phase relation.

D. the have the same wavelength.

Ahmad has a far point of a mere 50 cm. He uses a contact lens to see the distant object clearly. What is/are the condition(s) about the contact lens?

A. The contact lens is a concave lens.

B. The contact lens is a diverging lens.

C. The focal length of the contact lens is -50 cm.

D. The power of the contact lens is -2.0 D

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.