Reading Material and Learning Activity Sheet # 11

VARIOUS LIGHT PHENOMENA

Name of Learner: __________________________________ Grade 11/Section: ________________ Date: ________ Score: _____
MELC 11: • Explain various light phenomena such as: Your reflection on the concave and convex sides of
a spoon looks different, mirages, light from a red laser passes more easily though red cellophane than green
cellophane, clothing of certain colors appear different in artificial light and in sunlight, haloes, sundogs, primary
rainbows, secondary rainbows, and supernumerary bows, why clouds are usually white and rainclouds dark
and why the sky is blue and sunsets are reddish
How do different light phenomena occur?
Reflection on a Spoon
The two surfaces of a metal spoon are examples of a curved mirror. The front of the spoon that curves inward
represents a concave mirror while the back part which bulges outward is the convex mirror. When you try to
look into the front part of the spoon, you will see a smaller and inverted version of yourself. On the other hand, if
you look at the back part of the spoon, you will see a smaller but upright image of yourself. Why is this so?
Your image appears differently on both parts of the spoon because light reflects differently upon hitting the
concave and convex mirrors. When light rays hit the surface of a concave mirror, the rays tend to meet or
converge at the focal point of the mirror creating a real and inverted image. When light rays strike a convex
mirror, the rays tend to scatter or diverge from the focal point. This means the real rays will not meet and create
the image but the imaginary ones will converge and create the virtual and upright image.
Mirage
Have you ever experienced seeing a puddle of water where the sky is reflected on an asphalt road a few meters
in front of you while walking on a hot sunny day? And then when you pass over that part where the water is
supposed to be, there was none? This is referred to as heat haze or a highway mirage.
A mirage is an optical phenomenon which creates a displaced image of an object due to refraction of light. This
happens because the air just above the asphalt road has a higher temperature than the layer of air above it. The
differences in temperature cause differences in optical densities or refractive indices of the different layers of air
which bends or refracts light.
The image below is another example of a mirage. The
sunlight that hits the tree is reflected towards the
observer's eyes. Some reflected light rays that do not
pass through layers of air with differences in
temperature reach the observer's eyes without bending
(represented by the straight arrow coming from the
tree to the observer).
On the other hand, other reflected light rays will have to
travel through the layers of air with different
temperatures. The differences in the temperature of the
layers of air bends or refracts the reflected light rays
(represented by the curved broken line coming from
the tree to the observer). The refracted light rays
produce a displaced image of the tree or a mirage
(represented by the broken straight line coming from
the observer's eyes to the ground).
Filter
A filter can either be a colored glass or cellophane that absorbs certain frequencies of visible light and transmits
a particular color frequency that matches the filter's natural frequency. Light transmission occurs when a
transparent object allows light to pass through it.
When white light hits a blue glass, the glass will absorb all the color frequencies except for blue. When a red laser
hits a red cellophane, the cellophane will transmit red because their frequencies match. On the other hand, when
a red laser hits a green cellophane, the cellophane will absorb the red light instead of transmitting it because
their frequencies do not match.
Objects Under Sunlight and Artificial Light
The color of an object that we see depends on the reflected color frequency of visible light that reaches our eyes.
Different objects absorb and reflect different color frequencies. For example, the petals of a yellow bell appears
yellow because the petals absorb all the color frequencies of white light except for yellow which is reflected. The
reflected yellow light reaches our eyes that makes us see the color of the petals.
Objects reflect certain color frequencies based on the source that illuminates them. Incandescent light bulbs emit
lower frequency colors such as red, orange, and yellow. Thus, the objects with these colors are enhanced under
the incandescent light. On the other hand, higher frequency colors, such as blue, are emitted by fluorescent light
bubs. This means that a red shirt will appear more red under an incandescent light than in a fluorescent light. In
the same way, a blue shirt will appear more blue under a fluorescent light. We see the objects' "true" colors when
they are illuminated by sunlight or daylight.
Dark Rain Clouds
From the previous lesson, you have learned that clouds appear white because the water droplets in the clouds
scatter all the color frequencies of white light equally. On the other hand, rain clouds appear dark because they
are too thick that sunlight needs to pass through
a lot of water droplets and be absorbed before it
can reach the observer’s eye.
Reddish Sunsets
Recall that the atmospheric particles scatter
higher frequency light which makes the sky
appear blue. In a similar way, sunsets appear
red because sunlight travels a greater distance
as it reaches the horizon and encounters more
atmospheric particles, scattering higher
frequencies of light until only the red light is left.

Test Questions: Write the letter of the correct answer on the space before each number.
____1. What property of light is responsible for the occurrence of a mirage?
A. reflection B. scattering C. dispersion D. refraction
____2. It is a material that only allows specific color of light to pass through it.
A. filter B. wood C. metal D. clay
____3. In which of the following will a yellow flower appear yellow when observed behind it?
A. blue glass B. yellow glass C. red glass D. green glass
____4. Which side of the spoon is similar to a convex mirror?
A. the front part that curves inward B. the back part that curves inward
C. the back part that bulges outward D. either side of the spoon can be a convex mirror
____5. Which of the following best explains why clothes of a certain color appear differently under daylight and
incandescent light?
A. Daylight emits color of lower frequency light more than the higher frequency colors.
B. Daylight emits color of higher frequency light more than the lower frequency colors.
C. Incandescent light emits color of lower frequency light more than the higher frequency colors.
D. Incandescent light emits color of higher frequency light more than the lower frequency colors.
____6. Which of the following best explain why rain clouds are dark?
I. When light is reflected in the rain clouds, nothing reaches the observer’s eye.
II. Rain clouds contain a lot of water droplets which absorb all the frequencies of light.
III. When light is absorbed in the rain clouds, nothing reaches the observer’s eye.
IV. Rain clouds contain a lot of water droplets which reflect all the frequencies of light.
A. I and II B. II and III C. I and IV D. II and III
____7. Which of the following best explain why sunsets appear red?
I. Sunlight travels a greater distance as it reaches the horizon encountering lesser atmospheric particles.
II. Atmospheric particles scatter lower frequency light until only the red light is left.
III. Sunlight travels a greater distance as it reaches the horizon encountering more atmospheric particles.
IV. Atmospheric particles scatter higher frequency light until only the red light is left.
A. I and II B. II and III C. III and IV D. II and IV
____8. Which of the following best describes an image that is produced by the front of the spoon?
A. real and inverted B. real and upright C. virtual and inverted D. virtual and upright
____9. Arrange the following processes to explain how a mirage is formed.
a. The sunlight that hits an object is reflected off to the observer's eyes.
b. Some of the reflected light rays travel through layers of air with different temperatures.
c. Different temperatures of the layers of air cause light to be refracted creating a displaced image of the
object.
d. Some of the reflected rays travel in a straight line to the observer's eyes.
A. a,b,c,d B. c,b,d,a C. a,d,b,c D. b,c,a,b
Your friend looks at his reflection on a spoon. He describes his image as upright.
____10. On which side of the spoon is he observing his image?
A. back part B. front part
C. either back or front part D. Spoons do not reflect light.
How do haloes, sundogs, primary rainbows, secondary rainbows, and supernumerary bows
occur?
Haloes
Solar halo, which is also called gloriole, icebow or nimbus,
is a light phenomenon that happens when light shines
through clouds that are composed of ice crystals. Light
refracts upon passing through the ice crystals and also
reflects upon hitting the crystal’s faces; these events cause
the formation of the bright ring around the Sun or Moon.
Halo is usually bright white ring but may also have colors due
to the dispersion of light upon striking the ice crystals. Below
is a picture of a halo produced around the Sun.

Sundogs
Sundogs, or parhelion (with the sun), happen due to the
refraction of light upon hitting the small crystals that make up cirrus or cirrostratus clouds. These
crystals are hexagonal in shape and with faces almost horizontal upon drifting; these cause the
formation of spots of light (sundog) on either side of the Sun, or the Moon, when light strikes them at a
minimum angle of 22 degrees as shown in the image below. Since red light is the least refracted
compared to blue this makes the inner edge of a sundog to be red hued.

The image below shows an actual sundog which has a red-hued inner edge.

Rainbows
A rainbow is a light phenomenon formed from the combination of several light properties like
refraction, reflection, and dispersion. Rainbows are usually seen after rainfall because they are formed
when light strikes the scattered raindrops in the atmosphere.
As shown in the image below, light is refracted upon hitting a raindrop that serves as the prism. Due to
the differences in the frequency of the colors of visible light, they are refracted at different amounts and
are dispersed. The dispersed colors reflect upon hitting the other side of the raindrop and then refracted
again as they go out. The colors go out dispersed and reach the observer’s eyes.
Test Questions: Write the letter of the correct answer on the space before each number.
____1. What other names are used to mean the light phenomenon halo? Choose all that apply.
I. rainbow II. gloriole III. ice bow IV. nimbus
A. I and II B. I, II and III C. II, III and IV D. All of the above
____2. Which of the following correctly describes how a halo looks like?
A. Bright ring formed around the sun or moon.
B. Bright spots of light formed in either side of the sun or moon.
C. An arc of colors that forms opposite the sun.
D. An arc of light composed of green, pink and purple colors
____3. In the formation of sundogs, how should the ice crystals (which light strikes at an angle 22
degrees) be oriented as they drift?
A. The ice crystals are oriented vertically. B. The ice crystals are oriented horizontally.
C. The ice crystals are oriented diagonally to the right.
D. The ice crystals are oriented diagonally to the left.
____4. Why is the inner edge of a sundog red hued?
A. The inner edge of sundog is red hued because red is the color that is refracted the least.
B. The inner edge of sundog is red hued because red is the color that is refracted the most.
C. The inner edge of sundog is red hued because red is the color that is reflected the most.
D. The inner edge of sundog is red hued because red is the color that is reflected the least.
________5. What light phenomenon is seen usually after a rain shower when the atmosphere is filled
with tiny droplets of water?
A. sundog B. halo C. parhelion D. rainbow
____6. What rainbow is formed when light refract upon hitting a droplet of water and a single internal
reflection occurs in a droplet?
A. supernumerary rainbow B. tertiary rainbow
C. primary rainbow D. secondary rainbow
____7. Which of the following correctly distinguishes a primary rainbow and a secondary rainbow?
Choose all that apply.
I. The colors in the secondary rainbow are in the reverse arrangement compared to the colors in
the primary rainbow.
II. The secondary rainbow is fainter compared to the primary rainbow.
III. The secondary rainbow is wider compared to the primary rainbow.
IV. The secondary rainbow is as high as the primary rainbow from the ground.
A. I and II B. II and III C. III and IV D. I, II and III
____8. What causes the reverse of the colors in a secondary rainbow as compared to a primary
rainbow?
A. Secondary rainbow is formed when two internal reflections occurs causing the reverse of the
colors as compared to primary rainbow where single internal reflection happens.
B. Secondary rainbow is wider and fainter making the colors in reverse arrangement.
C. Secondary rainbow is formed when single internal reflection occurs causing the reverse of the
colors as compared to primary rainbow where two internal reflections happens.
D. Secondary rainbow is formed in front of a primary rainbow which makes the colors in reverse
arrangement.
____9. What condition must be satisfied in order for supernumerary rainbow to be formed?
A. Light must strike small droplets of water with different sizes.
B. Light must strike small droplets of water with almost the same sizes.
C. Light must strike droplets of water with various sizes.
D. Light must strike droplets of water with the same altitude from the ground.
____10. How are supernumerary rainbows unlike primary and secondary rainbow
A. Supernumerary rainbow is not composed of the seven colors.
B. Supernumerary rainbow does not form an arc.
C. Supernumerary rainbow is not after a rain shower.
D. Supernumerary rainbow is seen on the same side of the source of light.