Chapter 19, Problem 59A

(a)

To determine

The optical phenomenon for producing the color in bubbles.

Answer to Problem 59A

Thin film interference

Explanation of Solution

Introduction:

An optical phenomenon in which the superposition of two light waves results in the formation of new wave with greater, lower or the equal amplitude compared to original waves is called an interference. The interference may be constructive or destructive depending on the phase difference between the interfering waves.

A soap bubble can be treated as a thin film of soap and water. The soap bubble has a very small thickness that is in the order few wavelengths of visible light. A part of the light incident on the soap bubble gets reflected back and remaining portion of the light gets pass through it. The light rays that are reflected from the outer surface of the bubble experience wavelength shift to some extent and the light rays reflected by the inner surface is shifted by some more distance that it covered. This leads to interference between the two reflected rays and attractive color can be seen on the soap bubble.

(b)

To determine

The causes for color produced in rose petals.

Answer to Problem 59A

Pigments

Explanation of Solution

Introduction:

The beautiful colors of the flowers makes it to be get attracted by living beings. The pollinators such as honeybees, hummingbirds, and butterflies are having attraction towards the flowers only because of the presence of coloring pigments in it. The main cause for the color of flowers is the presence of certain coloring pigments in it. This may also get affected by certain other factors such as presence of metal ions in the flowers.

The presence of certain pigments gives color to the rose petals. Carotenoids and flavonoids are two main types pigments in flowers. Carotenoids mainly contains the pigment carotene that gives yellow, orange, and red color to the flowers. While flavonoids mainly contains the pigment anthocyanin that gives red, purple, magenta, and blue color to the flowers.

(c)

To determine

The optical phenomenon by which color is produced in oil films.

Answer to Problem 59A

Interference

Explanation of Solution

Introduction:

Interference of light waves is an optical phenomenon defined as the superposition of two light waves to produce a resultant wave with greater, lower or the equal amplitude.

The thickness of the oil films are in the order few wavelengths of visible light. The light rays reflected from the top surface of the oil film is shifted by some wavelength and the light rays reflected by the bottom surface is shifted by some extra distance that it covered. This leads to interference between the two reflected rays and beautiful color can be seen on the oil film.

(d)

To determine

The optical phenomenon by which color is produced in rainbow.

Answer to Problem 59A

Refraction

Explanation of Solution

Introduction:

Refraction of light waves is the change in direction or bending of light waves when it travels from one medium to another. The degree of refraction depends on the wavelength of light.

Rainbow is a spectrum of light appears in the sky and is forming due to the refraction of light rays from water droplets in the atmosphere.