Electromagnetic Waves: Nature, Production, and Transmission, High school final essays of Earth science

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Table of Contents

Page COVER PAGE COPYRIGHT PAGE TITLE PAGE TABLE OF CONTENTS

• What I Need to Know ……………………………….. Lesson 1: Uses of Plane Mirrors in Optical Devices
• What I Know …………………………………
• What’s In …………………………………
• What’s New …………………………………
• What is It …………………………………
• What’s More …………………………………
• What I Have Learned …………………………………
• What I Can Do …………………………………
• Lesson 1: Assessment …………………………………
• Additional Activities …………………………………
• What I Need to Know ……………………………….. Lesson 2: Uses of Curved Mirrors in Optical Devices
• What I Know …………………………………
• What’s In …………………………………
• What’s New …………………………………
• What is It …………………………………
• What’s More …………………………………
• What I Have Learned …………………………………
• What I Can Do …………………………………
• Lesson 2: Assessment …………………………………
• Additional Activities …………………………………
• What I Need to Know ………………………………… Lesson 3: Uses of Lenses
• What I Know …………………………………
• What’s In …………………………………
• What’s New …………………………………
• What Is It …………………………………
• What’s More …………………………………
• What I Have Learned …………………………………
• What I Can Do …………………………………
• Lesson 3: Assessment …………………………………
• Additional Activities …………………………………
• Assessment (Unit Test) …………………………………
• Key to Answers …………………………………
• References …………………………………

A. twice as its height B. equal to its height C. one half of its height D. four times as its height

3. A ray reflected from a retro-reflector A. passes through the focal point. B. forms a right angle with an incident ray. C. travels in the direction opposite that of the incident ray. D. has an angle of reflection equal to the angle of incidence.
4. A ray of light parallel to the optic axis of a concave mirror is reflected back A. through the focal point. B. parallel to the optic axis. C. as if it came from the focal point. D. through the center of the sphere.
5. The back surfaces of automobile headlights are curved A. to concentrate light in one direction. B. to get multiple images of the filament. C. for structural reasons not related to optics. D. because inverted, real images of filaments shine brighter.
6. A ray of light passing through the focal point at an angle to the optic axis of a concave mirror is reflected back A. through the focal point. B. parallel to the optic axis. C. in the horizontal direction. D. through the center of the sphere.
7. What type of image is formed when an object is placed at a distance of 1.5 focal lengths from a convex mirror? A. erect and real B. erect and virtual C. inverted and real D. inverted and virtual
8. Some yellow objects actually absorb yellow light but reflect red and green light. If we shine yellow light on such a yellow object, it will appear ...... to our eyes. A. black B. green C. red D. yellow

9. If a ray of light strikes a pane of glass at 45 degrees to the normal, it A. leaves the glass at a larger angle to the normal. B. leaves the glass at a smaller angle to the normal. C. passes straight through as if the glass were not there. D. leaves with the same angle to the normal, but is deflected to the side.
10. Two coins are at equal distances from your eye. One is under 40 cm of water, the other under 40 cm of glass. Which coin appears closer? A. Cannot be determined B. The one under the glass C. The one under the water. D. They both appear at the same distance.
11. The dispersion of light when it passes through a prism shows that A. all colors in the light are treated the same. B. the speed of light in a vacuum is a constant. C. different colors have different indices of refraction. D. the prism contains many narrow, equally spaced slits.
12. A converging lens is used to form a sharp image of a candle. If the lower half of the lens is covered by a piece of paper, the A. image will not change. B. image will become dimmer. C. lower half of the image will disappear. D. upper half of the image will disappear.
13. In most cameras the location of the image is adjusted to appear on the film by changing the A. shape of the lens. B. position of the lens. C. focal length of the lens. D. diameter of the diaphragm.
14. A human eye employs a _____ lens to form _____ images. A. diverging .... real B. converging .... real D. diverging .... virtual C. converging .... virtual
15. A camera employs a _____ lens to form _____ images. A. diverging .... real B. converging .... real C. diverging .... virtual D. converging .... virtual

The images that a plane mirror reflects are known as "virtual images" – but they are different from the simulated digital images that you can see on your computer screen or in a game on your phone. The difference between a real versus virtual image is that a real image is formed when light converges at a point – like looking at an apple on your desk – a virtual image is formed from two divergent rays of light which never meet. To simplify, a plane mirror creates an image of an object you cannot touch. This way, all mirrors create virtual images, but plane mirrors reflect light differently than concave or convex mirrors do. Image Source: https://commons.wikimedia.org/wiki/File:Plane-mirror.png Reflections from the plane mirror create upright virtual images with the same magnification or size and distance as the objects they reflect. That is why you can use a plane mirror to decide precisely where there is something behind you.

What is It

Application of Plane Mirrors Where are plane mirrors used?

1. Elevator Mirrors Elevators are one of the greatest products of technology, because going up 25 flights of stairs sounds tiring and time-consuming. If you thought that the creators of elevators were only concerned with the engineering part of it, you're definitely wrong. Installed mirrors are strategically placed for a great reason. Turns out, back in the day, when elevators were relatively new, people stood in them, staring into nothingness with an exaggerated sense of time because they had nothing else to do. All they could think of was their very natural fear of falling

from an elevator suspended mid-air with nothing but cables. So, mirrors were installed in order to distract people and give them something to look at while they waited. The mirrors also gave the usually small space of an elevator a sense of depth, thereby reducing the feeling of claustrophobia that one might feel in such an enclosed space. Image Source: https://www.storypick.com/elevators-mirrors-quora/ 2. Periscope A periscope is an instrument for observation over, around or through an object, obstacle or condition that prevents direct line-of-sight observation from an observer's current position. A simple periscope consists of an outer case with mirrors at each end set parallel to each other at a 45° angle. Periscopes allow a submarine, when submerged at a relatively shallow depth, to search visually for nearby targets and threats on the surface of the water and in the air. Image Source: https://blog.hubspot.com/marketing/these-brands-are-proving-how- effective-periscope-can-be

CAUTION: Be careful in handling mirrors since the edges might be sharp. . Procedure:

1. You may use 3 small rectangular mirror strips to form your kaleidoscope.
2. Connect the three rectangular mirror strips using a scotch tape to form a triangle

3. Cut your cardboard roll to the length of your mirror plus 1/3" (.

cm). This is with a box cutter, but scissors will do. Just be careful not

to stab yourself.

Image Source: https://www.wikihow.com/Make-a-Kaleidoscope, Accessed June 26, 2020

4. Create your peephole. Here's how: *Place one of the circular ends of your tube flat on a piece of paper -- contact paper is best, but construction paper or even gift wrap will work, too. *Cut about 1" (2.5 cm) around the traced circle; with that extra 1", cut little notches around the circle so it bends more easily (it'll sort of look like a firework). *Cut a triangle or circle in the center of the paper to view through. Center the cardboard tube on top of your circle and secure the edges with tape (unless you're using contact paper, of course). Image Source: https://www.wikihow.com/Make-a-Kaleidoscope, Accessed June 26, 2020

5. Create your plastic lenses. Get an empty plastic container or two and trace two circles using the end of your tube (permanent marker is easiest to see). With an object that's about ½" (1.25 cm) larger than your tube, draw around the previous ones. Then, cut around the each of the larger circles with scissors. Lenses! With one of the circles, cut notches all the way to the inside of the smaller circle -- this'll be called lens 1. It should sort of resemble a gear. With the other circle, cut notches to the outside tracing of the smaller circle — this'll be lens 2. Lay them flat against the table and bend the notches upwards. Image Source: https://www.wikihow.com/Make-a-Kaleidoscope, Accessed June 26, 2020

6. Assemble the inside of your kaleidoscope. To begin, slide your triangular mirror inside the cardboard tube. Take lens 1 and place it inside your tube against the edges of the mirror, notches facing up; this should form a sort of makeshift pouch. Place your selected beads, sequins, glitter, gems, and/or confetti on top of this plastic lens. Cap your gems using lens 2, notches facing down, and use masking tape to secure it all together. Image Source: https://www.wikihow.com/Make-a-Kaleidoscope, Accessed June 26, 2020

1. Decorate your tube. The easiest way to make this kaleidoscope look as

impressive as possible is contact paper -- so long as you work out the

paper that it would read correctly when you place it in front of a

mirror.

ENJOY!!!!!!!!

Video Title: Lateral Inversion: Why is ‘Ambulance’ written in reverse Channel: It’s AumSum Time Link: https://www.youtube.com/watch?v=bjlYKvQo-kI Image Source: https://www.youtube.com/watch?v=bjlYKvQo-kI Based on the video you have watched or based on the activity you have performed, explain in your own words, why the word ‘Ambulance’ is written in reverse in this emergency vehicle?

Lesson 1: Assessment

Now after learning about plane mirrors, answer the following questions based on what you have learned from this lesson. Choose the letter of the best answer. Write the chosen letter on a separate sheet of paper.

1. The dispersion of light when it passes through a prism shows that

A. all colors in the light are treated the same.

B. the speed of light in a vacuum is a constant.

C. different colors have different indices of refraction. D. the prism contains many narrow, equally spaced slits.

2. A ray reflected from a retro-reflector A. passes through the focal point. B. forms a right angle with an incident ray. C. travels in the direction opposite that of the incident ray. D. has an angle of reflection equal to the angle of incidence.

3. A ray of light parallel to the optic axis of a concave mirror is reflected back A. through the focal point. B. parallel to the optic axis. C. as if it came from the focal point. D. through the center of the sphere.

4. The back surfaces of automobile headlights are curved A. to concentrate light in one direction. B. to get multiple images of the filament. C. for structural reasons not related to optics. D. because inverted, real images of filaments shine brighter.

5. In most cameras the location of the image is adjusted to appear on the film by changing the: A. shape of the lens. B. position of the lens. C. focal length of the lens. D. diameter of the diaphragm.

6. A ray of light passing through the focal point at an angle to the optic axis of A concave mirror is reflected back: A. through the focal point. B. parallel to the optic axis. C. in the horizontal direction. D. through the center of the sphere. 7.What happens to the image produced by a pinhole camera when you move the back wall farther from the pinhole? It becomes A. larger and brighter. B. larger and fainter. C. smaller and brighter. D. smaller and fainter.

   8. The shortest mirror in which a creature from outer space can see its entire body is _________________________.

15. A camera employs a _____ lens to form _____ images. A. diverging .... real B. converging .... real C. diverging .... virtual D. converging .... virtual

Additional Activities

Activity 1. 3 The Simple Periscope Task: Construct a simple periscope and trace the incident and reflected rays. Materials:

1. Plane mirrors – 2 pcs
2. Illustration board or cardboard
3. Cutting Mat
4. Glue or sticky tape
5. Cutter, scissors, ruler, flashlight or lamp Procedure:
6. Using the materials listed, design and construct an improvised periscope based on the information gathered from different resources.
7. A record sheet is provided to serve as your guide for accomplishing the written report on your constructed periscope. Image Source: https://www.youtube.com/watch?v=hDDisOh4oZE

ACTIVITY SHEET

Name:_________________________________ Grade and Section:_______________________ Sketch the device/model constructed: What concepts did you learn in the construction of the device? Explain

Lesson

Uses of Curved Mirrors in

Optical Devices

What I Need to Know

Now that you already understand what optical devices are and how plane mirrors are used in these devices, it’s now time to learn something new. Aside from plane mirrors, we also have another classification of mirrors known as the curved mirrors (spherical mirrors). There is also a wide array of optical devices using the curved mirrors. Let us explore more with the succeeding items. After going through this lesson, you are expected to: 1.Identify ways in which the properties of curved mirrors determine their uses in optical instruments.

What’s In

In this lesson, you will learn how curved mirrors are used in devices utilized by scientists and even ordinary people like you. You will have a broader understanding on how curved mirrors are widely used in our day to day living and how they play a significant role in technology.

What’s New

Concave and Convex Mirrors In contrast to plane mirrors, convex and concave mirrors curve the rays of light that hit them. This results in the virtual images produced by their reflections coming out distorted, as the light rays move towards or away from the center of the mirror. For this reason, convex and concave mirrors aren't useful in bathrooms, but they can be helpful in the right situation; for example, because plane mirrors can't produce useful images at certain angles, the mirrors on the side of a car are convex. They allow drivers to see behind and to the sides of their vehicle, though these virtual images aren't at the same distance as the objects they reflect. This is why car mirrors have messages reminding drivers that objects in the mirror may be closer than they appear in the reflection. Convex mirrors curve outwardly. Light rays diverge as they reflect off the curve of this mirror; when the rays converge again, the viewer sees an image. Convex mirror images are upright and appear farther away than they really are. Image Source: https://www.sciencelearn.org.nz/images/48-convex-mirror

Concave mirrors curve inwardly. Light rays diverge off the curve of this mirror. The image may be upside down if the object is too far away. When the object is close to the mirror, it appears right side up and magnified. (2) Image Source: https://www.sciencelearn.org.nz/images/47-concave-mirror

What is It

Application of Curved Mirrors Where are curved mirrors used?

1. Side Mirrors (Motorcycle or Car) One of the most important safety devices on your vehicle is its set of mirrors. It might be considered the simplest but it plays a great role in ensuring your safety on the road. A side mirror, also known as the wing mirror, is a mirror placed on the outside of motor vehicles to help the driver see areas behind and to the sides of the vehicle, outside the driver's peripheral view known as the "blind spot”. Image Source: https://unsplash.com/s/photos/side-mirror