Light, Shadows, and Reflection PDF

LIGHT, SHADOWS AND REFLECTION NB LESSON OBJECTIVES To explain the difference between luminous and illuminated objects and describe how light travels. To use examples of natural phenomena, such as eclipses and pinhole cameras, to demonstrate how shadows and images are formed. T...

LIGHT, SHADOWS AND REFLECTION NB LESSON OBJECTIVES To explain the difference between luminous and illuminated objects and describe how light travels. To use examples of natural phenomena, such as eclipses and pinhole cameras, to demonstrate how shadows and images are formed. To compare and contrast the properties of shadows and images, explaining how mirrors form clear images and how pinhole cameras capture images differently. NB KEY WORDS luminous object Solar eclipse Illuminated objects Lunar eclipse Bioluminescence Virtual image Solar energy Converging beam Translucent Diverging beam Transparent Rectilinear propagation Opaque NB  Shall we make a rainbow? Instructions: Hold the prism in front of the light source (flashlight or sunlight). Direct the light through the prism onto a white surface (wall or paper). Slowly rotate the prism to find the angle where the light splits into a rainbow. Observe the colors that appear and note how the position of the prism affects the rainbow.  A luminous object is an object that emits Illuminated objects do its own light. not produce light themselves; instead, they reflect light from luminous objects NB Is this object luminous or Bioluminescence is the production and emission of illuminated? Flashlight? light by living organisms. It Candle? occurs through a chemical Neon? reaction in which an enzyme Telescope? called luciferase acts on a Galaxy? molecule called luciferin, Glowworm? producing light. Laser? Bulb? Star? Mirror? NB Light is a Source of Energy: Solar energy: Light from the Sun provides solar energy, which can be harnessed for power through solar panels. Natural source: Sunlight is a natural source of light and energy, driving processes like photosynthesis in plants. Keeps Earth warm: The Sun's light helps keep Earth warm, enabling life by maintaining the planet’s temperature.  How would life on Earth be affected if solar energy were suddenly unavailable? Consider its impact on plants, animals, and human activities. NB A light year is a unit of distance used in astronomy to describe how far light travels in one year. Since light moves at a speed of approximately 299,792 kilometers (or about 186,282 miles) per second, a light year equals about 9.46 trillion kilometers (or 5.88 trillion miles). It is used to measure vast distances between celestial objects, such as stars and galaxies. OBJECTS AND SHADOWS NB OBJECTS Transparent. Translucent Opaque Allows some light to Does not allow light Allows light to pass pass through, but to pass through; through completely, objects behind objects behind so objects behind appear blurry or cannot be seen at can be seen clearly. Clear glass, clean water unclear. all. Frosted glass, wax paper Wood, metal, brick When is shadow formed? A shadow is formed when an opaque object blocks the path of light. Here are the key points about when and how shadows are created: Light Source: A shadow occurs in the presence of a light source, which can be natural (like the Sun) or artificial (like a lamp). Opaque Object: Only opaque objects can create shadows because they do not allow light to pass through them. Positioning: The position of the object in relation to the light source affects the size and shape of the shadow. Shadows are typically longer when the light source is low in the sky (such as during the morning or evening) and shorter when the light source is directly overhead. Surface: Shadows are cast on a surface, and the texture and color of that surface can influence how the shadow appears.  SUBJECT ENRICHMENT ACTIVITY H:W EUREKA ACTIVITY TEXT BOOK PAGE NUMBER:165 POST YOUR IMAGES IN GC  Lets think…. Why do you think artists and photographers pay attention to shadows in their work? What would happen if you used a translucent object instead of an opaque one? Can shadows be used to tell time? How do sundials utilize the concept of shadows? https://youtu.be/U2vZN3WcnbQ NB  An eclipse is a celestial event that occurs when one opaque body, such as the Moon or Earth, blocks the light from another body, resulting in a shadow. Opaque Bodies: Both the There are two main types of Moon and Earth are opaque, eclipses: meaning they do not allow Solar Eclipse: Occurs when the light to pass through. Moon passes between the Earth and the Sun, blocking the Sun's Day and Night Formation: light. Eclipses can illustrate how the Lunar Eclipse: Occurs when the alignment of the Moon and Earth passes between the Sun and Earth affects the formation of the Moon, casting a shadow on the day and night. Moon. NB A solar eclipse occurs when the Moon moves between the Earth and the Sun, blocking all or part of the Sun's light from reaching the Earth. Total Solar Eclipse: The Moon completely covers the Sun, and the Sun's corona (outer atmosphere) becomes visible. This can only be seen from a specific area on Earth. Partial Solar Eclipse: Only a portion of the Sun is obscured by the Moon. Observers in different locations will see varying degrees of coverage. Occurrence: Solar eclipses occur during a new moon phase when the Sun and Moon align. However, not every new moon results in an eclipse because the Moon's orbit is tilted relative to the Earth's orbit around the Sun. NB NB A lunar eclipse occurs when the Earth passes between the Sun and the Moon, causing the Earth's shadow to fall on the Moon. Total Lunar Eclipse: The entire Moon passes through the Earth's umbra (the darkest part of its shadow), causing the Moon to appear reddish or coppery in color, often referred to as a "Blood Moon.“ Partial Lunar Eclipse: Only a portion of the Moon enters the Earth's umbra, resulting in part of the Moon being darkened while the rest remains illuminated. NB Occurrence: Lunar eclipses occur during a full moon phase when the Sun, Earth, and Moon are aligned. Unlike solar eclipses, lunar eclipses can be seen by anyone on the night side of the Earth.  Light travels in straight lines through a uniform medium, a behavior known as rectilinear propagation. Because of rectilinear propagation, we can predict the paths of light and the formation of shadows and reflections. A beam of light is a stream of light rays traveling in the same direction. When visualized, a beam appears as a straight line, demonstrating the concept of rectilinear propagation. Evidence for Rectilinear Propagation: Shadow Formation: The formation of shadows demonstrates that light travels in straight lines. When an opaque object blocks a light source, it creates a distinct shadow on the surface behind it, illustrating that light cannot bend around the object. NB  ACTIVITY TIME TEXT BOOK PAGE No: 168 Why Does a Mirror Form a Clear Image? A mirror forms a clear image due to the reflection of light rays that strike its surface. A mirror has a shiny surface that reflects light. When light rays from an object hit the mirror, they bounce back. This bouncing effect allows us to see ourselves or other objects clearly in the mirror. The image we see in a mirror is called a virtual image. This means the image appears to be behind the mirror but isn't actually there. The smoothness of a mirror’s surface is essential. A smooth surface reflects light evenly, which helps create a clear image. If the surface were rough, the light would scatter, making the image blurry. NB  Let’s discuss.. What is the difference PISA between an image and a THINK PAIR AND SHARE shadow? ACTIVITY. TEXTBOOK PAGE No: 172  Pinhole camera A pinhole camera is a simple tool that shows how light travels in a straight line. It consists of a small box with a tiny hole on one side and a translucent screen on the opposite side. Light passes through the pinhole and forms an inverted image of objects outside the camera on the screen inside. This device does not use lenses but still creates clear images, helping to understand basic light and shadow principles. Lets think…. In what situations might you see a shadow instead of an image? Why do you think solar and lunar eclipses are not visible from all parts of the Earth at the same time? What happens when shadow of the earth falls on moon? When does such an event occur? A plane mirror forms a clear image but a rough floor does not. Explain why. NB