PHYSICAL SCIENCE QUARTER 4

VARIOUS LIGHT

PHENOMENA

It is a fundamental part of our everyday experience and plays a crucial role in how we perceive the world around us.

In this lesson, we will learn more about light and it's behaviour.

Light is not only in darkness!

In this lesson, students are expected to explain various light phenomena such as:

• Your reflection on the concave and convex sides of a spoon;
• Clothing of certain colors appear different in artificial light and sunlight;
• Mirages, Haloes, sundogs, primary rainbows, secondary rainbows, and supernumerary bows;
• Why clouds are usually white and rainclouds dark.
• Why the sky is blue, and sunsets are reddish.

Learning Objectives

Directions: Read the questions carefully and analyze the pictures on the screen. Try to apply the concepts about light from our previous lesson.

REVIEW!

1. What are the two nature of light?

Wave and Particles

Directions: Read the questions carefully and analyze the pictures on the screen. Try to apply the concepts about light from our previous lesson.

REVIEW!

2. Rene Descartes explained the phenomena of refraction in rainbows. In his experiment, what material did he use to produce a rainbow?

Spherical glass filled with water.

Directions: Read the questions carefully and analyze the pictures on the screen. Try to apply the concepts about light from our previous lesson.

REVIEW!

3. A phenomena by which an objects partially submerged in water appears to be distorted or bent.

Refraction

Directions: Read the questions carefully and analyze the pictures on the screen. Try to apply the concepts about light from our previous lesson.

REVIEW!

4. When sunlight enters the atmosphere of the Earth, the atoms and molecules of different gasses present in the air absorb the light. Then these atoms re-emit light in all directions which causes the color of the sky.

Scattering of Light

Directions: Read the questions carefully and analyze the pictures on the screen. Try to apply the concepts about light from our previous lesson.

REVIEW!

5. When two or more waves of light interact, they can either reinforce or cancel each other out.

Interference

Note: Kindly bring out the any mirror you have in your pockets.

Images in a plane mirror are usually formed behind or inside the mirror and its location remains the same regardless of the observer's location.

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To understand more of this concept, use a plane mirror and place an object in front. What can you observe to the image reflected by the mirror?

Note: Kindly bring out the any mirror you have in your pockets.

Image formed in the mirror is the result of light rays that are reflected from the object to the mirror.

Any object you place in front of a plane mirror, the image will have the same size or height and same orientation.

Thus, the image formed in a plane mirror is Virtual, Upright and Same Size.

Note: Kindly bring out the any mirror you have in your pockets.

Thus, the image formed in a plane mirror is Virtual, Upright and Same Size.

Note: Kindly bring out the any mirror you have in your pockets.

TERMS TO REMEMBER

Virtual - if the image is formed inside the mirror, usually happens if the image formed is the same size or reduced.

Real - if the image is formed outside the mirror, usually happens if the image formed is enlarged.

Upright - the orientation of the object and image is the same.

Inverted - the orientation of the object and image is different.

Note: To understand more of the concept, kindly bring out your smooth surface silver spoon.

What do you see in the pictures to your right?

What do you think is the reason behind the formation of those image?

Note: To understand more of the concept, kindly bring out your smooth surface silver spoon.

A spoon both have concave and convex surfaces producing both real and virtual images respectively.

The image formed depends on which side of the spoon you are using. How does it work?

Note: To understand more of the concept, kindly bring out your smooth surface silver spoon.

The front of the spoon is a concave reflecting surface that produces real and inverted images.

A concave mirror is a mirror with a curved surface that bulges inward.

It is also known as a converging mirror because it converges or brings parallel light rays together after reflection.

Note: To understand more of the concept, kindly bring out your smooth surface silver spoon.

P

P’

C

R

V

Note: To understand more of the concept, kindly bring out your smooth surface silver spoon.

Concave mirrors are used in telescopes, where they gather and focus light to create magnified images. They are also used in makeup mirrors, headlights, solar furnaces, and reflector antennas.

Note: To understand more of the concept, kindly bring out your smooth surface silver spoon.

Applications of Concave Mirrors

Note: To understand more of the concept, kindly bring out your smooth surface silver spoon.

The back of the spoon is a convex reflecting surface that produces virtual and upright images.

A convex mirror is a mirror with a curved surface that bulges outward.

Note: To understand more of the concept, kindly bring out your smooth surface silver spoon.

P

P’

C

R

V

Note: To understand more of the concept, kindly bring out your smooth surface silver spoon.

Convex mirrors are commonly used in situations where a wide field of view and safety are important. They help drivers see a wider area in their rear-view mirrors, and they are used for security and surveillance purposes to provide a broader perspective.

Note: To understand more of the concept, kindly bring out your smooth surface silver spoon.

Application of Convex Mirror

PICTURE ANALYSIS

Note: Mirage usually appears during a hot sunny day.

Mirage is the deceptive appearance of a distance objects cause by the bending of light rays of air of varying density and temperature.

Note: Mirage usually appears during a hot sunny day.

Light is bent (refracted) when it moves through the cold air and into the layer of hot air.

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In that way, the light refracted comes to our eyes in different angles and elevation causing us to see illusions.

Note: Mirage usually appears during a hot sunny day.

In an experiment about light using red and green lasers with red and green gummy bears.

THE GUMMY BEAR EXPERIMENT!

THE GUMMY BEAR EXPERIMENT!

Observation #1: The green laser passes through the red gummy bear but cannot pass through the green gummy bear.

THE GUMMY BEAR EXPERIMENT!

Observation #2: The red laser passes through the green gummy bear but cannot pass through the red gummy bear.

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What do you think is the reason behind the phenomena?

Note: This part will help you understand the relationship between light and colors.

Remember that a prism spreads white light into its various component wavelengths or colors.

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This observable in prism, diamonds and water.

Note: This part will help you understand the relationship between light and colors.

Light of certain wavelengths (colors) are absorbed and reflected, with the reflected wavelength visible to the observer.

Note: Good lighting really brings out the beauty.

Have you ever noticed a difference in colors of objects particularly fabric under different sources of light?

Note: Good lighting really brings out the beauty.

Colored objects appear different under neutral light compared to artificial lights like flourescent, LED lamps, or even fire light.

Note: Good lighting really brings out the beauty.

Sunlight is a white light, which means it contains all visible light colors. Color has its own wavelength in the visible spectrum of light.

Note: Good lighting really brings out the beauty.

Artificial lights cannot have all the colors of the natural light spectrum. It misses other wavelengths resulting in the transmission of inaccurate or dull colors.

Rainbows result from the refraction of sunlight in falling water droplets plus the reflection of the light from the back of the droplet.

Note: There's a rainbow always after the rain - South Border

Rainbows are not only observable after the rain, you can also see rainbows in waterfalls. You just need to look for the right angle.

Note: There's a rainbow always after the rain - South Border

The primary rainbow resulted from one reflection inside the water droplet. The secondary rainbow is caused by a second reflection inside the droplet.

Note: There's a rainbow always after the rain - South Border

Note: "Baby, I can see your halo". - Beyonce

Also known as ice bow or nimbus, it happes when light shines through ice crystal clouds, forming a bright ring around the sun or moon. Haloes are typically bright white and have shades.

Known as a mock sun or phantom sun, it produces bright spots of light in the sky, often on a luminous ring or halo on either side of the sun. The refraction of light creates it.

Note: Sun dogs really make the Sun look dashing.

Note: Sky is not the limit.

In a cloud, sunlight is scattered by much larger water droplets. These scatter all colors almost equally making the clouds to appear white. (Mie Scattering)

Note: Sky is not the limit.

When light reaches the sky, blue light is scattered away more strongly than other colors making the sky blue. (Rayleigh Scattering)

Note: Sky is not the limit.

During sunsets, the sun's rays must travel a greater distance through the atmosphere. As light enters our eyes, it primarily consists of yellow, orange, and most importantly, red.

Look Further!

Any questions?