Optics & Waves

A:

An echo occurs when a sound wave reflects back towards its source after hitting a hard surface. Although the surface may absorb some of the sound, the remaining sound that is not absorbed continues moving, creating additional echoes by bouncing off surrounding objects until the sound is completely absorbed or dissipates.

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  • How fast is supersonic speed?

    Q: How fast is supersonic speed?

    A: Supersonic speed is faster than the speed of sound, which is 768 miles per hour at sea level. Some familiar objects capable of traveling that quickly are bullets, whips and jet planes.
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  • What is the highest frequency a human can hear?

    Q: What is the highest frequency a human can hear?

    A: Humans can generally hear frequencies from 20 to 20,000 hertz. However, under ideal laboratory conditions, humans have been able to hear frequencies as low as 12 hertz. As humans get older or are exposed to loud sounds that damage their hearing, the highest frequency they can hear decreases.
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  • What are some examples of sound energy?

    Q: What are some examples of sound energy?

    A: Examples of sound energy include sounds made by singing, whistling, musical instruments and horns. Sound is a vibration that causes a wave of pressure through air, water, wood and other mediums. It is heard when the wave reaches the ear and is perceived by the brain. Sound waves have characteristics including their frequency, amplitude, intensity, speed, direction and wavelength.
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  • What are the parts of a transverse wave?

    Q: What are the parts of a transverse wave?

    A: Parts of a transverse wave include the crest, trough, amplitude and wavelength. The crest is the top of the wave, and the trough is the bottom. The amplitude refers to the height of the wave from the midpoint, or rest point, of the wave. The wavelength is the length it takes for the wave to complete one cycle.
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  • What is the frequency range of radio waves?

    Q: What is the frequency range of radio waves?

    A: Radio waves range from 300 gigahertz (GHz), or a wavelength of 1 millimeter, to 3 kilohertz (kHz), which corresponds to a wavelength of 100 kilometers. Radio waves are the lowest frequency within the electromagnetic spectrum. The wavelength is the distance from the peak of one wave to the next.
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  • How does an echo occur?

    Q: How does an echo occur?

    A: An echo occurs when a sound wave reflects back towards its source after hitting a hard surface. Although the surface may absorb some of the sound, the remaining sound that is not absorbed continues moving, creating additional echoes by bouncing off surrounding objects until the sound is completely absorbed or dissipates.
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  • How does a kaleidoscope work?

    Q: How does a kaleidoscope work?

    A: A kaleidoscope works by reflecting light that bumps into a reflective surface such as a mirror. It has two or more mirrors placed at an angle to each other. The mirror assembly is surrounded by a case, with an eyehole at one end of the mirrors and a collection of objects at the other end.
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  • What is the distance between wave crests?

    Q: What is the distance between wave crests?

    A: The distance between wave crests is called wavelength. It is a characteristic shared by waves of all kinds, including ocean waves and sound waves. Wavelength is measured from the highest point, or summit, of one wave's crest to the summit of the next wave's crest.
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  • How do X-rays work?

    Q: How do X-rays work?

    A: X-rays work by passing electromagnetic radiation through the body to create an image on film or on a digital device, thus providing diagnostic imaging. They are a part of the electromagnetic spectrum that includes visible light, ultraviolet light and infrared red heat. X-rays are shorter in wavelength than visible light and heat.
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  • Why do lights appear to flicker from a distance?

    Q: Why do lights appear to flicker from a distance?

    A: The flickering or twinkling effect of lights when observed from a distance is caused by anomalous refraction as light passes through air, schlieren, where temperatures and densities vary. The technical term for this phenomenon is called "scintillation," and it refers to the rapid changes in the position and color of a distant object.
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  • How do waves carry energy from one place to another?

    Q: How do waves carry energy from one place to another?

    A: Energy is transferred in electromagnetic waves by vibrations in electric and magnetic fields. The vibration of air particles is energy transfer in sound waves, while the transfer of energy in water waves is the oscillation of water particles.
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  • What is a hand lens?

    Q: What is a hand lens?

    A: A hand lens is used to magnify items. Hand lenses are used in scientific research, police work and everyday life. Hand lenses are magnifying glasses small enough to be held in a hand and easy to manipulate.
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  • What is infrared used for?

    Q: What is infrared used for?

    A: Infrared is used for keeping things warm, reading information and checking heat. The uses for infrared technology are so diverse because infrared not only detects heat but produces heat in objects that it strikes.
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  • What is the speed of light in water?

    Q: What is the speed of light in water?

    A: The speed of light in water is approximately 225,000 km per second. While enormously fast, this is notably slower than the speed of light in a vacuum, which is 300,000 km per second.
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  • How does sound travel through a medium?

    Q: How does sound travel through a medium?

    A: Sound travels as a back-and-forth vibration of the particles of its medium. It is a longitudinal mechanical pressure wave that varies greatly in its speed of travel and the distance it remains coherent, dependent upon the medium. Sound in air travels relatively slowly and for a short distance, while sound in a solid, such as the primary waves of an earthquake, travel extremely quickly and to great distances.
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  • What is Snell's law of refraction?

    Q: What is Snell's law of refraction?

    A: Snell's law of refraction is the relationship between the angles of incidence and refraction with respect to the refraction indices of two different media. Snell's law of refraction can be applied to the refraction light for any two media. Snell's law predicts the angle of refraction that light follows when passing from one medium and into the next medium.
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  • Why doesn't sound travel through a vacuum?

    Q: Why doesn't sound travel through a vacuum?

    A: Sound does not travel through a vacuum because molecules of matter are required for sound to exist, and vacuums do not have any matter. The vibrations and movements of small particles of matter are what create sound and allow it to be heard. In a vacuum without any matter, such as space, it is impossible for sound to travel.
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  • How do magnifying glasses make things look bigger?

    Q: How do magnifying glasses make things look bigger?

    A: An observer's perception of an object being examined changes with a magnifying lens because the lens bends the light rays from the object, thus distorting the size of the image formed, making it appear bigger. Light rays bend due to a change in density as they move from air to the glass that forms the lens. If light rays did not bend, no magnification would occur.
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  • How is light transmitted through glass?

    Q: How is light transmitted through glass?

    A: When light passes through glass, the photons in the light interact with the electrons in the glass. However, photons in visible light don't have enough energy in them to change the state of electrons in glass, so the light just passes through the glass.
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  • Can light bend?

    Q: Can light bend?

    A: Yes, light can bend through diffraction and refraction. Diffraction is when light bends around a corner or a small opening and fills the larger space beyond it. Refraction is the bending of light when it transitions through different mediums, such as light seen in the air and entering into water.
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  • How do we see light?

    Q: How do we see light?

    A: The human eye sees light with the pupil and the retina. Located inside the retina are two types of special cells called photoreceptor cells. There are two varieties of photoreceptor cells known as cones and rods.
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