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Project

1-Wire Weather Station

The weather station in this project is quite basic, measuring only temperature, pressure, and humidity, but it may be easily expanded to measure other weather components, such as wind speed and rainfall. The design is based on using a series of…

Project

3x3x3 LED Cube

LEDs (light-emitting diodes) are rectifying semiconductor devices that convert electrical energy into electromagnetic radiation. You can use these devices to create a 3-dimensional light display. LED cubes require some care and good soldering skills…

Project

Arduino Oscilloscope

An oscilloscope is a device that allows you to see an electronic signal so that it appears as a waveform. Traditional oscilloscopes work by amplifying a signal to control the position of a dot on the y-axis (vertical axis) of a cathode-ray tube…

Project

Chatbot, an Artificially Intelligent Microcontroller

The term "Chatbot" is used for a computer or computer program that is made to emulate some form of human intelligence through conversation. In this project, you will learn how easy it is to make a specific microcontroller—an Arduino™ Uno—seem as…

Project

Laser-Grid Intruder Alarm

This is a working alarm. It uses a laser beam that bounces between mirrors attached to two walls that face each other. The figure to the right has been digitally edited to show the path of the beam. When the beam is broken, a buzzer sounds.This…

Project

Levitation Machine

This project allows you to use electromagnetic levitation to suspend a globe of the world above a surface. The "globe" is actually a table tennis ball painted to look like a globe. Keeping it in place requires careful control of electrical current…

Project

Pulse Generator Circuit

A pulse generator circuit is an important building block for many electronic projects, such as the heart of a digital clock. Its purpose is basically to switch an output on and off for as long as the circuit is activated. Sometimes, these circuits…

Project

Text-Controlled RGB LED

A red, green, and blue (RGB) light-emitting diode (LED) is a useful electronic component that can produce visible light in a variety of colors. This is done by varying the intensity of the light output of the three different color LED elements (red,…

Project

Theremin-like Instrument

A theremin is a musical instrument developed in the 1920s by the Russian inventor, Léon Theremin. It was one of the world's first electronic musical instruments. The original invention used radio-frequency electronics and a pair of antennae. By…

Project

White-Noise Generator

White noise is a smooth hiss consisting of all audio frequencies played back at random simultaneously. Because your ears cannot "lock" onto any specific frequencies or patterns in white noise, this device has the effect of shutting off your ears to…

Project

Constant-Speed Vehicle

Everything in the universe is in motion. One basic, yet important, type of motion is constant-speed motion. This project takes you through assembly of a model battery-powered vehicle that moves at a constant speed. This particular vehicle is built…

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from article Ohmmeter

Electronic digital ohmmeter. (Tinsley)

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from article Ohmmeter

Diagram of ohmmeter, showing operating principles. C1, C2 = current terminals; P1, P2 = potential terminals.

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from article Ohmmeter

Special measuring probes (Kelvin clips), consisting of a set of leads with combined current probes (C1, C2) and potential probes (P1, P2).

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from article Cavity resonator

Closed-end sound pipe resonating (a) at the fundamental frequency f1 (the first harmonic) with wavelength λ1, and (b) at an overtone, f3 ≈ 3f1 (the third harmonic), with wavelength λ3.

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from article Cavity resonator

Wavemeters. (a) Wavemeter consisting of cylindrical cavity with an adjustable end-wall, resonating in the TE011 mode. The free-space wavelength λ0 corresponding to the resonant frequency f0 is given by λ0 = 2L[1 + (2L/1.64a)]− 1 2 . (b) Practical…

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from article Cavity resonator

Determination of the Q of a cavity resonator by (a) measuring the bandwidth and (b) measuring the damping rate of the oscillations.

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from article Lens (optics)

Refraction of light waves demonstrated by the disjointed appearance of a spoon entering a bowl of water, as well as the transposition of background colors due to the bowl's curvature. (Credit: Copyright © McGraw Hill)

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from article Lens (optics)

Illustration of a standard concave lens (left) that acts as a diverging lens and a standard convex lens (right) that acts as a converging lens.

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from article Ctenothrissiformes

A Cretaceous ctenothrissiform fossil, Ctenothrissa sp. (order Ctenothrissiformes), on a limestone matrix found in Lebanon. Size: 90 mm (3.5 in.). (Photo courtesy of The Virtual Fossil Museum)

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from article Dewar flask

Two typical Dewar containers.

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from article Animal testing

Mice are the most commonly used vertebrate species in animal testing and research. (Credit: Dolores Bonaparte)

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from article Animal testing

The use of animals in biomedical research remains essential, but the handling of these sentient beings must be done humanely to minimize and prevent animal harm. (Credit: U.S. Department of Agriculture)

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from article Propagator (field theory)

Feynman diagrams for scattering processes. (a) Electron-proton scattering via photon exchange. (b) Proton-proton scattering via meson exchange.

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from article Conservation of energy

The conservation of energy allows energy to be interconverted among many different forms. In the use of wind power, for example, the kinetic energy of wind (movements of air) can be converted by turbine blades into electrical energy. (Credit: Ron…

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from article Electrical units and standards

Calculable capacitor. (a) Cross section of general cylindrical capacitor with four segments. (b) Cross section of symmetrical capacitor with cylindrical electrodes. (c) Calculable capacitor used in absolute determination of the ohm. (U.S. National…

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from article Electrical units and standards

Moving-coil balance. (a) Schematic diagram. (b) Equipment. (U.K. National Physical Laboratory)

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from article Electrical units and standards

Josephson effect. (a) Josephson junction characteristic. (b) Linear array of more than 2000 Josephson junctions in a folded microwave stripline, giving a total voltage step in the region of 1 volt. (U.S. National Institute of Standards and…

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from article Electrical units and standards

Quantum Hall effect. (a) Geometry of semiconductor. (b) Hall resistance characteristic. i = quantum number.

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from article Acari

Parasitiformes body plan. Lateral view of a predatory adult female Mesostigmata showing major body regions and important structures. Scale bar = 0.1 mm (0.004 in.). (Scanning electron micrograph by D. E. Walter)

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from article Acari

Acariformes body plan. (a) Adult female Oribatida (Sarcoptiformes) in lateral view showing major body regions and important structures. (b) Hexapod larva (Trombidiformes): dorsal view of a chigger, a parasite of vertebrates. (c) Octopod deutonymph…

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from article Triple point

Phase diagram for water, showing gas, liquid, and several solid (ice) phases; triple points at A, B, and C. The pressure scale changes at 101 kilopascals from logarithmic scale at low pressure to linear at high pressure.

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from article Inertial confinement fusion

Ablative indirect drive and ablative direct drive. (a) In laser-illuminated, ablative indirect drive, the ICF target consists of a cylindrical hohlraum (hollow room) in which laser light is injected through the two holes in the end caps and heats…

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from article Inertial confinement fusion

X-ray images with a framing camera (developed at Lawrence Livermore National Laboratory) from a directly driven inertial confinement fusion capsule at the University of Rochester's Omega Facility. The camera has 80-ps exposure time and 55-ps time…

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from article Inertial confinement fusion

Deuterium–tritium fuel ion temperature and density at ignition, plotted against normalized radius, for a typical high-gain capsule.

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from article Inertial confinement fusion

The National Ignition Facility (NIF) at Lawrence Livermore National Laboratory (LLNL). Its driver is the world's largest laser. The 1.8 MJ of ultraviolet light (351-nm wavelength from frequency-tripled neodymium:glass laser light) is generated with…

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from article Inertial confinement fusion

Progress toward ignition on NIF is illustrated by the plot of no-burn D–T equivalent yield in number of neutrons versus the value of ρr inferred from the energy lost by fusion neutrons during passage out of the compressed fuel. These experiments…

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from article Inertial confinement fusion

View of the combined Z Machine and Z-Beamlet laser facility (lower left) with exploded view of the cross section of the Z Machine (upper left). Both will be used to drive the MagLIF capsule (right) at Sandia National Laboratories. The 10-kJ…

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from article Inertial confinement fusion

Computed capsule gains (energy yield divided by absorbed energy) from 1D simulations of the principal (radial) dynamics for ablative direct drive of a perfect capsule, which is irradiated by either 248-nm laser light or 351-nm laser light with…

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from article Inertial confinement fusion

Electra, an ∼500 J/pulse, electron-beam pumped KrF laser at the Naval Research Laboratory. It has achieved 90,000 shots in a continuous run and 330,000 shots in 8 days at 2.5–5 Hz.

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from article Inertial confinement fusion

Conceptual design of the X-target. (Credit: Heavy Ion Fusion Science Virtual National Laboratory)

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from article Renner-Teller effect

Bending potential function V for a degenerate electronic state of a linear molecule as a function of displacement r, and for three values (0, 0.5, 1.0) of the Renner parameter ε. In the absence of Renner-Teller splitting (ε = 0) there is a single…

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from article Capacitance

Parallel-plate capacitor P1, P2 with guard ring GG. Spacing between guard ring and plate is exaggerated. (a) Cross section with all parts of capacitor at ground potential. (b) Top view showing plate P1 surrounded by guard ring. (c) Cross section of…

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from article Capacitance

Variable air capacitor.

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from article Capacitance

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from article Capacitance

Wound-roll construction of plastic film and paper capacitors.

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from article Capacitance

Ceramic capacitor constructed in chip form, showing cutaway of finished chip.

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from article Capacitance

Tantalum electrolytic capacitor showing cross section. (General Electric Co.)

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from article Capacitance

Construction and polarity markings of aluminum electrolytic capacitor. (a) Cross section. (b Polarization markings for tabular capacitor with axial leads. (c) Polarization markings for capacitor with radial leads. (After A. Mottershead, Electricity…

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from article Capacitance

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from article Haplosporida

Spore of Urosporidium fuliginosum.

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from article Haplosporida

Stages in the development of Icthyosporidium giganteum.

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from article Hyperbolic geometry

Examples of simple hyperbolic knots and links. (a) Figure-8 knot. (b) Whitehead link.

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from article Transmission lines

Two common transmission lines for communication. (a) Coaxial cable. (b) Strip line.

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from article Transmission lines

Equivalent circuit that represents three sections of a lossless transmission line. Each section is of length Δz, and has an inductor (L) and capacitor (C). Voltages (V ) and currents (I ), and their differences (ΔV and ΔI ) between successive…

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from article Transmission lines

Signal detection on an oscilloscope. (a) Oscilloscope pictures of voltage pulses at three locations, z1, z2, and z3, on a transmission line, successively more distant from the signal generator. (b) Oscilloscope pictures of a periodic voltage sine…

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from article Transmission lines

Transmission line with characteristic impedance Zc, terminated in a load impedance ZL. A change of coordinate system (from z to ζ) is indicated.

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from article Transmission lines

Envelope of the voltage standing wave consisting of a wave propagating from z = −∞ and being reflected at z = 0. The wavelength, λ, and the maximum and minimum voltages, Vmax and Vmin , are indicated.

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from article Transmission lines

Two waveguides, with conventional coordinates. (a) Rectangular waveguide. (b) Cylindrical waveguide.

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from article Transmission lines

Dispersion curve for a rectangular waveguide of width a, showing relationship between the propagation constant, β, and the angular frequency, ω. Here, n specifies the mode of propagation, and c is the speed of light.

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from article Transmission lines

Equivalent circuit of a power transmission line. The single-phase circuit is used to represent balanced three-phase lines. Here, R and X are the resistance and reactance (at the operational frequency), and C is the capacitance of the entire…

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from article Urodela

A typical member of the order Urodela: the longtail salamander (Eurycea longicauda). (Credit: Ryan Hagerty/U.S. Fish and Wildlife Service)

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from article Urodela

Southern dwarf siren (Pseudobranchus axanthus), which has undergone limb degeneration and retains only tiny forelimbs. (Credit: U.S. Geological Survey)

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from article Urodela

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from article Urodela

California tiger salamander (Ambystoma californiense). (Credit: John Cleckler/U.S. Fish and Wildlife Service)

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from article Urodela

The two-toed amphiuma salamander (Amphiuma means). (Credit: Southeast Ecological Center, U.S. Geological Survey)

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from article Urodela

The northern red salamander (Pseudotriton ruber ruber) is a member of the family Plethodontidae. (Credit: Alicia Lafever/U.S. National Park Service)

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from article Curie temperature

Variation of spontaneous magnetization of a ferromagnetic material with temperature.

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from article Curie temperature

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from article Reactance

Circuit with a resistor and capacitor in parallel.

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from article Chamois

Alpine chamois (Rupicapra rupicapra). (Photograph courtesy of Brent Huffman/Ultimate Ungulate Images)

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from article Chicxulub impact crater

Bouguer gravity anomaly map over the Chicxulub impact crater. The coastline is designated by a thin white line, cenotes (natural pits) and sinkholes are designated by black dots, and the city of Mérida and the town of Chicxulub Puerto are designated…

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from article Chicxulub impact crater

Seismic line imaging of what lies beneath the seafloor, showing the Chicxulub impact crater. The crater includes many faults that can be grouped into an exterior ring fault, a series of outer ring faults, and a series of inner ring faults. Within…

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from article Open channel

Types of open-channel flow. The inverted triangles denote the free surface of the flow. (a) Unsteady flow. (b) Steady, uniform flow. (c) Steady, gradually varied flow (GVF) and steady, rapidly varied flow (RVF). (After T. W. Sturm, Open Channel…

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from article Amniota

Basic types of vertebrate eggs.

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from article Amniota

Embryo developing in amniote eggs.

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from article Integrated optics

Optical waveguide. (a) Optical intensity of the fundamental guided mode. (b) Ray picture of the guided mode.

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from article Integrated optics

Two-dimensional transverse waveguiding. (a) Rib waveguide. (b) Diffused channel guide.

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from article Integrated optics

Prism input coupling and grating output coupling. With the ray directions reversed, the grating acts as an input coupler and the prism as an output coupler.

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from article Integrated optics

A “4 by 4” directional coupler switch.

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from article Integrated optics

Top view of an integrated optics spectrum analyzer.

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from article Integrated optics

A wavelength-division-multiplexed transmitter chip. DFB indicates distributed feedback.

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from article Muffler

Mufflers. (a) Reactive muffler for automobile exhaust system. (b) Dissipative muffler for industrial application.

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from article Muffler

Simple muffler elements and their representative transmission losses. (a) Helmholtz resonator. (b) Side-branch resonator. (c) Expansion chamber. (d) Expansion chamber with dissipative material.

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from article Mecoptera

Male scorpion fly (Panorpa), order Mecoptera.

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from article Conservation of mass

Charcoals burning. According to the principle of the conservation of mass, assuming the burning charcoals and the oxygen enabling their burning are all within a closed system, the total amount of mass in the system prior to the charcoals burning…

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from article Aharonov-Bohm effect

Aharonov and Bohm's proposed experiments to demonstrate the effects of electromagnetic potentials in electron interference phenomena. (a) Experiment to verify the effect of a vector potential. (b) Experiment to demonstrate the effect of a scalar…

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from article Aharonov-Bohm effect

Very small ring fabricated from a gold film 38 nm thick. Lines forming the ring are 40 nm wide, and the average diameter is 0.82 μm. The electrical resistance is measured by applying a constant current through two of the leads connecting the sample…

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from article Aharonov-Bohm effect

Resistance oscillations observed in the ring of Fig. 1 at temperature of 0.01 K over a very small magnetic field range. Vertical scale measures deviation ΔR of resistance from its mean value R. The period of the h/e Aharonov-Bohm oscillations in…

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from article Ursa Minor

Modern boundaries of the constellation Ursa Minor, the Little Bear. The celestial equator is 0° of declination, which corresponds to celestial latitude. Right ascension corresponds to celestial longitude, with each hour of right ascension…

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from article Optical fibers

Types of optical fiber designs. (a) Multimode, stepped-refractive-index-profile. (b) Multimode, graded-index-profile. (c) Single-mode, stepped-index. Graded-index is possible. (d) Microstructured optical fiber. (e) Hollow-core fiber for high-power…

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from article Optical fibers

Loss mechanisms in silica-based fibers.

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from article Venus

Venus compared to Earth in size. Note that the image of Venus at left does not include the planet's thick, opaque atmosphere. The image was obtained by the Magellan spacecraft that orbited Venus from 1990 to 1994. Magellan used cloud-penetrating…

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from article Venus

Venus viewed in visible light by the Galileo spacecraft during a 1990 gravity assist flyby on the probe's ultimate journey to Jupiter. (Credit: NASA)

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from article Venus

Global Venus clouds, as viewed in the ultraviolet from Venus Express. These features can be used to track winds and atmospheric motion at the cloud tops. Convection clouds can be seen near the equator (top of image), whereas streaky brighter clouds…

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from article Venus

Inhomogeneities in the total thickness of the clouds between 48 and 70 km (30 and 43 mi) show up in the near-infrared. These clouds, seen only at night, are backlit from the hot atmosphere below it (similar to a Chinese lantern), where bright…

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from article Venus

Perspective view of the southern boundary of Laksmi Planum, a plateau 2.5–4.0 km (1.5–2.5 mi) high. (Credit: NASA/JPL)

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from article Venus

Magellan image of the central and northern parts of the highland region Ovda Regio (north at top). Ridges running approximately east-west (horizontally) have been interpreted as resulting from crustal shortening (compression). Ridges are cut by…

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from article Venus

Perspective view of a portion of the Western Eistla Regio, with a rift valley in the foreground and the volcanoes Gula Mons (right) and Sif Mons (left) on the horizon. (Credit: NASA/JPL)

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from article Venus

Sapas Mons, one of several large volcanic edifices that compose the broad equatorial rise known as Alta Regio. (Credit: NASA/JPL)

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7,646 results

1-Wire Weather Station

3x3x3 LED Cube

Arduino Oscilloscope

Chatbot, an Artificially Intelligent Microcontroller

Laser-Grid Intruder Alarm

Levitation Machine

Pulse Generator Circuit

Text-Controlled RGB LED

Theremin-like Instrument

White-Noise Generator

Constant-Speed Vehicle

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