Search Results: "Harvard Natural Sciences Lecture Demonstrations"

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02:32
Jumping Wire

39 views / 0 likes - added 4 months ago

A current-carrying wire interacts with an external magnetic field. The direction of the force is perpendicular to both the current and the magnetic field. The battery is a 12 Volt gel cell. The wires have a total resistance of about 0.1 Ohms. The magnetic
01:18
Circular Motion vs Mass on Spring

47 views / 0 likes - added 4 months ago

Simultaneous shadow projection of circular motion and an oscillating mass on a spring. We see that the vertical component of the circular motion is identical to that of the vertically oscillating mass. This simple harmonic motion can be mathematically mod
Flame Tests of Metals

153 views / 0 likes - added 2 years ago

Qualitative demonstration of how salts of various metalssodium, lithium, potassium, calcium, strontium, barium, and copperemit characteristic colors when burned in a flame. We can analyze the component colors by placing a 500 lines/cm diffraction film in
04:55 Popular
Nylon Synthesis

1,072 views / 0 likes - added 3 years ago

A classic science demonstration of two-component polymerization, nylon 66 (also known as "nylon 6,6") is pulled from the interface of two solutions: Hexamethyldiamine in 0.5M sodium hydroxide solution is the lower layer, and adipoyl chloride in cyclohexan
06:03 Popular
pH Buffer Solution

732 views / 0 likes - added 3 years ago

We have four containers with universal indicator: Two of them are mixed with distilled water, the other two mixed with a buffer solution of ammonia and vinegar. We compare the pH changes when we add dropper-fulls of 1M NaOH and HCl to the dishes. We see t
01:39
Limiting Reagent Vinegar or Baking Soda?

270 views / 0 likes - added 3 years ago

Vinegar and two different amounts of baking soda in plastic soda bottles with balloons.Two 500ml soda bottles of the same make, split a bottle of vinegar between them.11" balloons are pre-inflated with dry air, with care taken not to stretch the neck of t
02:43
Metals in Acid

445 views / 0 likes - added 3 years ago

Curly strips of zinc and magnesium are dropped into 2M hydrochloric acid, and bubbles of hydrogen gas are observed as a result of the reactions.For more details on our setup, see https://sciencedemonstrations.fas.harvard.edu/presentations/metals-acidThank
02:59
55 Gallon Drum Collapse from Vacuum

537 views / 0 likes - added 3 years ago

When the air inside a 55 gallon steel drum is pumped out, we see the weight of the atmosphere push inward with 101 kPa of pressure. The top and bottom of the drum has a radius of about 30 centimeters, and it is about 1 meter tall. This means the atmospher
01:25
Sodium Absorption Lines

422 views / 0 likes - added 3 years ago

Burning of sodium bicarbonate in Bunsen flame produces sodium absorption lines in continuous spectrum. Sodium 'D' line absorption shows up as a black line in the yellow of a continuous spectrum. Good as a simulation of the sodium portion of the Fraunhoffe
03:38
Cloud Chamber

317 views / 0 likes - added 3 years ago

The trajectories of individual charged particles leave behind cloudy trails as they ionize the cooled, supersaturated air-alcohol vapor inside this diffusion cloud chamber. Alpha particles from the radioactive decay of an inserted 2% thorium alloy rod for
14:05
Relativity Train

319 views / 0 likes - added 3 years ago

The Relativity Train is a realization of the famous Einstein thought experiments involving traveling trains carrying clocks and meter sticks. The demonstration is used to show how the preservation of the postulated constancy of physical laws and the speed
05:20
Chaotic Waterwheel

236 views / 0 likes - added 3 years ago

A waterwheel with leaky buckets undergoes chaotic motion. Our wheel is about 1 meter in diameter and was fabricated with wood in our shop. The little buckets are citronella candle holders with holes drilled out of the bottom. The sump pump was purchased f
01:50 Popular
Total Internal Reflection in Water "Bucket of Light"

709 views / 0 likes - added 3 years ago

A beam of laser light can be trapped inside a stream of water by suffering total internal reflectionthe aquatic equivalent of a fiber optic cable. In our setup we have a 2-liter soda bottle with a hole cut into the side. The bottle is filled with water an
00:52
Mousetrap Fission Setup

262 views / 0 likes - added 3 years ago

Woflgang and Allen quickly and efficiently prepare the Mousetrap Fission demo for Robert Kirshner's The Energetic Universe course on February 26, 2015. The demo consists of 110 mousetraps armed with ping-pong balls; the demonstrator drops a single ball fr
00:40
Vacuum Cannon

317 views / 0 likes - added 3 years ago

High speed footage of a ping pong ball, propelled by air rushing into an evacuated tube, penetrating three empty soda cans. The PVC tube is 8 feet long and 1.5 inches in diameter, with a layer of mylar sealing both ends. The ball accelerates down the tube
02:12
Fire Tornado

461 views / 0 likes - added 3 years ago

A story of one man's love of a fire tornado demonstration. A small metal container sits in the center of a 13" diameter turntable. Bending and clamping a brass screen (10 wires per inch) around the perimeter of the turntable forms a 36" tall cylinder. Iso
04:34
Ultrasonic Levitation

221 views / 0 likes - added 3 years ago

Acoustic levitation meets Schlieren optics: By reflecting a sound wave back onto itself, one can secure a standing wave if the distance between the source of the sound and the reflector is equal to an integral number of half wavelengths. In this demonstra
03:49
Coanda Effect

665 views / 2 likes - added 3 years ago

Fluids flowing near a surface tend to follow the shape of the surface. Using Schlieren optics, we can see this behavior. It is known as the Coanda Effect and its explanation depends on viscosity, the frictional forces between the molecules of a fluid (be
04:59
Visualizing Ultrasound with Schlieren Optics Part I

296 views / 0 likes - added 3 years ago

Part 1 of 3. We use a schlieren optics system with a strobing light source to visualize ultrasonic waves emitted by a transducer driven at a frequency of 28 kHz.Images employing schlieren optics are very sensitive to changes in the density of air. Since s
02:57
Visualizing Ultrasound with Schlieren Optics Part II

239 views / 0 likes - added 3 years ago

Part 2 of 3. We use our strobing schlieren system to look at diffraction and standing wave patterns in air created by an ultrasonic transducer (driven at 28 kHz) and a reflecting glass plate.More information about our schlieren optics set-up and how it wo
05:59
Visualizing Ultrasound with Schlieren Optics Part III

254 views / 0 likes - added 3 years ago

Part 3 of 3. We combine the stroboscopic effect with the use of color filters in our schlieren optics setup to visualize the changes in air pressure that occur in a standing wave created by an ultrasonic transducer (driven at 28 kHz) and a reflecting glas
04:34
What Does Acoustic Interference Look Like?

209 views / 0 likes - added 3 years ago

We use the strobing schlieren effect to visualize acoustic interference between two 28 kHz sound waves. Recognizing where constructive interference must take place allows us to interpret bright bands of light that appear in the continuously illuminated sc
04:35
Launch Lab, a conservation of momentum experiment

320 views / 0 likes - added 3 years ago

Nils gives a demonstration and description of the Launch Lab. The experiment is a variation on a ballistic pendulum--instead of a projectile colliding with the pendulum, it is ejected from it. The platform consists of a section of Masonite, a clothes pin,
02:46
Meissner Effect

479 views / 0 likes - added 5 years ago

A permanent magnet begins to hover above a ceramic material as it cools and transitions to a superconducting state; the magnet remains aloft until the ceramic warms above a critical temperature. The ceramic material is a 25mm disc of yttrium barium copper

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