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Questions and Answers
Which electromagnetic wave is primarily used in microwave ovens for heating food?
Which electromagnetic wave is primarily used in microwave ovens for heating food?
What type of light production involves the emission of light due to the absorption of ultraviolet light, with a delayed emission?
What type of light production involves the emission of light due to the absorption of ultraviolet light, with a delayed emission?
In what context is chemiluminescence most suitable due to its minimal heat production?
In what context is chemiluminescence most suitable due to its minimal heat production?
Which type of electromagnetic wave is used in medical imaging?
Which type of electromagnetic wave is used in medical imaging?
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What form of light production relies on electricity passing through a gas?
What form of light production relies on electricity passing through a gas?
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Which application is NOT a use for ultraviolet radiation?
Which application is NOT a use for ultraviolet radiation?
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Which of the following scenarios would benefit most by using phosphorescence?
Which of the following scenarios would benefit most by using phosphorescence?
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Which of the following electromagnetic waves has the shortest wavelengths?
Which of the following electromagnetic waves has the shortest wavelengths?
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According to the laws of reflection, what is the relationship between the angle of incidence and the angle of reflection?
According to the laws of reflection, what is the relationship between the angle of incidence and the angle of reflection?
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Which of the following best describes specular reflection?
Which of the following best describes specular reflection?
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If an incident ray strikes a plane mirror at an angle of 35° to the normal, what is the angle between the reflected ray and the mirror's surface?
If an incident ray strikes a plane mirror at an angle of 35° to the normal, what is the angle between the reflected ray and the mirror's surface?
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What is the speed of light in a material with a refractive index of 1.92, given the speed of light in a vacuum is approximately $3.00 \times 10^8$ m/s?
What is the speed of light in a material with a refractive index of 1.92, given the speed of light in a vacuum is approximately $3.00 \times 10^8$ m/s?
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What are the characteristics of an image formed by a concave mirror when an object is placed between the center of curvature (C) and the focal point (F)?
What are the characteristics of an image formed by a concave mirror when an object is placed between the center of curvature (C) and the focal point (F)?
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When light travels from one transparent material to another, what phenomenon occurs besides refraction?
When light travels from one transparent material to another, what phenomenon occurs besides refraction?
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The critical angle is the angle of incidence that results in which type of refraction angle?
The critical angle is the angle of incidence that results in which type of refraction angle?
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According to the content, when is no image produced by a concave mirror?
According to the content, when is no image produced by a concave mirror?
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What is the phenomenon of refraction?
What is the phenomenon of refraction?
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Under what condition does total internal reflection occur?
Under what condition does total internal reflection occur?
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If the critical angle for a plastic is 42 degrees, what would most likely happen to a light ray incident at 23 degrees?
If the critical angle for a plastic is 42 degrees, what would most likely happen to a light ray incident at 23 degrees?
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When light travels from air into glass, how does the refracted ray bend?
When light travels from air into glass, how does the refracted ray bend?
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Zircon has an index of refraction of 1.92. What does this value indicate?
Zircon has an index of refraction of 1.92. What does this value indicate?
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A convex lens is placed a distance 2F away from an object. Where is the created image, in relation to the lens and what are its basic characteristics?
A convex lens is placed a distance 2F away from an object. Where is the created image, in relation to the lens and what are its basic characteristics?
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What is a primary use for convex mirrors due to their image characteristics?
What is a primary use for convex mirrors due to their image characteristics?
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Study Notes
Electromagnetic Waves and Applications
- Radio waves are used for AM/FM radio, TV signals, cellphones, radar, and astronomy.
- Microwaves are used in telecommunications, microwave ovens, and astronomy.
- Infrared waves are used in remote controls, lasers, keeping food warm, and physical therapy.
- Visible light is used in human vision, theatre/concert lighting, and rainbows.
- Ultraviolet light causes tanning and sunburns, increases skin cancer risk, produces vitamin D, and kills bacteria.
- X-rays are used for medical imaging, security equipment, and cancer treatment.
- Gamma rays are used in cancer treatment and come from some nuclear decay.
Light Production Methods
- Electric discharge produces light by passing electricity through a gas (e.g., neon signs).
- Fluorescence produces light immediately by absorbing UV light (e.g., highlighters).
- Incandescence produces light due to high temperatures (e.g., incandescent light bulbs).
- Phosphorescence emits light over a long period after absorbing UV light (e.g., glow-in-the-dark stickers).
- Chemiluminescence involves a chemical reaction that creates light without producing significant heat (e.g., glow sticks).
Light Production Scenarios
- Near explosives: Chemiluminescence is best because it doesn't generate heat.
- Entertainment venues: Chemiluminescence (glow sticks) or electric discharge (neon signs) are useful.
- Underwater: Chemiluminescence or waterproof LED flashlights are suitable as they don't require electricity.
Laws of Reflection
- The angle of incidence equals the angle of reflection.
- The incident ray, reflected ray, and normal are in the same plane.
Specular vs. Diffuse Reflection
- Specular reflection occurs from smooth, shiny surfaces.
- Diffuse reflection occurs from dull, irregular surfaces.
Plane Mirror Reflection
- If the angle of incidence is 35°, the angle of reflection is also 35°.
- The angle between the mirror and the incident ray is 90° - 35° = 55°.
Ray Diagrams and Image Characteristics
- Ray diagrams show how light reflects/refracts for object-mirror/lens systems.
- Image characteristics (SALT) describe the image:
- Size: Larger, smaller, or same size as the object.
- Attitude: Upright or inverted.
- Location: Relative to the mirror/lens.
- Type: Real or virtual.
Concave Mirror Image Properties
| Object Location | Size | Attitude | Location | Type |
|---|---|---|---|---|
| Beyond C | Smaller | Inverted | Between C and F | Real |
| At C | Same | Inverted | At C | Real |
| Between C & F | Larger | Inverted | Beyond C | Real |
| At F | No image formed | |||
| Inside F | Larger | Upright | Behind mirror | Virtual |
Refraction
- Refraction is light bending when passing from one medium to another.
- Light bends toward the normal when entering a denser medium.
- Light bends away from the normal when entering a less dense medium.
Index of Refraction
- A higher refractive index means slower light.
- The index of refraction (n) relates speed of light (c) to the speed in the medium (v): n = c/v.
Partial Reflection and Refraction
- Some light is reflected, some refracted when passing between transparent materials.
Critical Angle and Total Internal Reflection
- The critical angle is the angle of incidence that produces a 90° angle of refraction.
- Total internal reflection occurs when the angle of incidence exceeds the critical angle (light stays in the denser medium).
Lenses
- Ray diagrams for lenses show how light refracts.
Convex Mirror Applications
- Convex mirrors increase field of view, making them useful in security mirrors (stores, parking garages), and side mirrors on cars because a broader view of surroundings creates safety.
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Description
Explore the fascinating world of electromagnetic waves and their applications, including uses of radio waves, microwaves, and X-rays. Additionally, learn about various methods of light production like electric discharge and fluorescence. Test your knowledge on how these concepts shape our daily lives.
