Waves 472 Principle of lift Waves Color mixing The eye's memory

  • Issue: April 1993
  • Designer: N. & M. Eshel
  • Stamp size: 25.7 x 40 mm
  • Plate no.: 185
  • Sheet of 8 stamps Tabs: 4
  • Printers: E. Lewin-Epstein Ltd.
  • Method of printing: Offset

The Israel National Museum of Science Daniel & Matilda Recanati Center, Haifa

Recognizing that high technology and scientific advancement are the key to Israel's economic independence and security, the Museum is dedicated to the preparation of today's young people for tomorrow's world.

The Museum has, therefore, undertaken a mandate of national scope and importance and is determined to fulfil its commitment:

Founded in 1983, the Museum is housed in the original building of the Technion - Israel Institute of Technology. Located in the heart of Haifa, this historic, innovative structure has been restored to its pristine beauty and transformed into a world of wonder and creativity.

The Museum and its programs have earned national recognition and an international reputation for excellence and innovation in science education.

Dedicated to making the complicated easily understood, the National Museum of Science is a "user-friendly", touch-and-feel institution. The Albert Einstein Hall of Science is the Museum's central exhibition space, comprising 4000 sq. meters over three floors. Here, child and adult alike, "learn" by doing, as they play with more than 200 unique, dynamic exhibits in the Museum's permanent collection. As everyone gets into the action, scientific principles - no longer frustrating - become a source of fun and fantasy.

Not lust a repository for past glories and present achievements, the Museum is a window to the future. Not just a building, the Museum reaches out beyond its walls - to towns and villages throughout Israel, to touch the minds and imaginations of young and old.

In addition to its permanent collection, the Museum regularly offers temporary exhibitions covering a wide range of issues and areas of interest.

A series of lectures for the general public on topics of science and technology is a regular feature of the Museum's program.

Mixing colored lights (Color Mixing)

The exhibit in the museum demonstrates additive color mixing, and the concept of complementary colors. Mixing any two of the three primary colors, or all three, using appropriate intensities, yields any color. In this exhibit the intensities are regulated so, that mixing all three lights renders white. The overlapping zone of any two circles appears as the complementary of the third color.

A projected slide - no screen (The Eye's Memory)

The visitor turns the wheel with a handle and observes a projected slide. When the rotation is fast enough, a clear picture is obtained. This phenomenon results from a property called the eye's memory. The eye remembers each picture for a small period of time and combines the sequence of pictures on the wheel to achieve one constant picture.

The Bloomfield Science Museum Jerusalem

The Bloomfield Science Museum aims at opening the eyes of visitors of all ages and backgrounds to the wonderful phenomena of science and technology and to the joy of understanding them.

The Museum's facilities and activities include permanent and temporary "hands-on" exhibitions, a Garden of Science, a Discovery Center for younger children, demonstrations, do-it-yourself activities, films, lectures and a Science Theater.

In the Museum there are no signs saying "Don't touch" or "Do not approach".

The exhibits attract and intrigue, and the atmosphere excites the will to discover and to be involved. A cultured museum-goer has learned to suppress these impulses, and must re-discover them in the Science Museum, where touching, pressing and pulling are encouraged.

The Museum opened in July 1992 with an exhibition entitled "Change and Movement". The visitor makes waves in a rope, in a "ladder", in water; plays with a tornado, a whirlpool, and bubbles in water; discovers how pendulums transfer energy to each other; and many other phenomena.

In the Discovery Center, an exhibition called "Discover Machines" lets young children activate various machines, feel magnetic forces on their feet, and enjoy the strange effects of lenses and mirrors.

Kindergarten and school children are offered organized "Science Days" made up of various activities. Parent-child workshops and Science Stories take place in the Discovery Center. Various "outreach" activities are in planning.

Floating ball (The Principle of Lift)

The force that keeps the ball from falling Out of the air stream is the same as that which holds up birds and airplanes. In any flowing fluid, the pressure decreases as the speed increases. In this exhibit, when the ball tries to move sideways out of the air stream, the air pressure on the side of the ball outside the stream becomes higher than on the side inside the stream, so the ball gets pushed back into the stream.
Because of the shape of a wing, the air is forced to flow faster over the top of the wing than under it, so the pressure is lower above the wing than below it, and the wing is pushed upwards.

Wavy ladder (Waves)

What goes up must come down - including waves. In this exhibit, one swings one of the arms and watches the resulting wave go up to the ceiling and "bounce" back down. There are many wave phenomena in nature and in technology. These generally work on the same principle as this one: Each element (usually a molecule) pushes or pulls on its neighbour, which acts on its next neighbour, and so on. The waves move through the material, the material does not move with the wave. Light and radio waves are not actually carried by any material. The idea that there can be a wave without anything to carry it is very difficult to accept, and for a hundred years scientists have been searching - unsuccessfully - for an "ether" to carry the light wave.

top top

Illustration of scientific concepts