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Questions and Answers
What is the angle of reflection equal to in the Law of Reflection?
What is the angle of reflection equal to in the Law of Reflection?
What is the purpose of a ray diagram?
What is the purpose of a ray diagram?
What type of image is formed by rays that appear to be coming from a certain position, but are not actually coming from this position?
What type of image is formed by rays that appear to be coming from a certain position, but are not actually coming from this position?
What is the term for the change in direction of a light ray when it bounces off a surface?
What is the term for the change in direction of a light ray when it bounces off a surface?
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What is the normal in a ray diagram?
What is the normal in a ray diagram?
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What happens to the image in a plane mirror?
What happens to the image in a plane mirror?
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What is the term for the substance through which light travels?
What is the term for the substance through which light travels?
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What is the characteristic of an image formed by a plane mirror?
What is the characteristic of an image formed by a plane mirror?
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What is the process by which hydrogen atoms in the Sun's core release vast amounts of energy?
What is the process by which hydrogen atoms in the Sun's core release vast amounts of energy?
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What is the type of light emitted by a material when it is at a high temperature?
What is the type of light emitted by a material when it is at a high temperature?
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What is the process by which mercury atoms emit ultraviolet light?
What is the process by which mercury atoms emit ultraviolet light?
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What is the term for light that is generated without heating the object?
What is the term for light that is generated without heating the object?
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What is the type of light that is generated by a biochemical reaction in a living organism?
What is the type of light that is generated by a biochemical reaction in a living organism?
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What is the term for the distance from one crest to the next in a light wave?
What is the term for the distance from one crest to the next in a light wave?
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What is the speed of light in a vacuum?
What is the speed of light in a vacuum?
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What type of light uses less energy and lasts longer than incandescent light?
What type of light uses less energy and lasts longer than incandescent light?
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Study Notes
Sources and Nature of Light
- All sources of light involve absorbing energy to raise atoms to an excited state, which then release energy as light.
- In the Sun's core, hydrogen atoms collide and fuse to form helium, releasing vast amounts of energy in the form of light through fusion reactions.
Types of Light
- Incandescent light is emitted when a material is heated to high temperatures, such as in incandescent light bulbs.
- Fluorescence occurs when a source is exposed to ultraviolet light, causing phosphor to emit visible light.
- Electrons excite Mercury atoms, which release UV light.
- UV light excites phosphor, producing visible light.
- Fluorescent lights are energy-efficient and last longer than incandescent bulbs.
- Luminescence is light generated without heating an object, using energy from various sources.
Phosphorescence and Chemiluminescence
- Phosphorescence is a type of luminescence where excited atoms retain energy for minutes to hours.
- Many glow-in-the-dark objects contain phosphorescent materials.
- Chemiluminescence is light generated by energy released in a chemical reaction without a rise in temperature, such as in glowsticks.
Bioluminescence
- Bioluminescence is light produced by a biochemical reaction in a living organism.
Properties of Light
- Light is the only form of energy that can travel as a wave through empty space and some materials.
- Light waves are electromagnetic waves that travel at 3 x 10^8 m/s in a vacuum.
- Wavelength is the distance between two consecutive crests.
- Electromagnetic spectrum is a diagram that illustrates the range of electromagnetic waves, ordered by wavelength or frequency.
Reflection
- Reflection is the change in direction of a light ray when it bounces off a surface.
- Light travels in a straight line in the same medium.
- Medium is the substance through which light travels.
- Ray diagrams can be used to make predictions about object appearances.
Law of Reflection
- The incident ray, reflected ray, and normal always lie on the same plane.
- The angle of reflection is equal to the angle of incidence (∠reflection = ∠incidence).
Mirrors
- Plane mirror has a flat reflective surface.
- Virtual image is an image formed by rays that appear to come from a certain position, but do not actually come from that position.
- Image does not form a visible projection on a screen.
- Our brain thinks the light rays are coming straight from an object behind the surface.
- Lateral inversion occurs in plane mirrors, where the image is reversed left to right.
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