Ultraviolet Photography with a Box Camera

April 6, 2010

Marty Sagendorfby:  Martin Sagendorf

Taking a photo in the UV is relatively easy and produces a somewhat different view of what we see in visible light.  All that’s required is a small bi-convex lens, a cardboard box, some pieces of thin cardboard, a pack of ‘Sun Paper’, and patience.

Ultraviolet Photography with a Box Camera - Educational Innovations BlogAs we know, sunlight contains ultraviolet, visible, and infrared ‘colors’, and we can ‘see’ only the middle wavelengths of this ‘optical spectrum’.  Infrared is invisible, but we feel it as heat and likewise, at the other end of the spectrum (at much shorter wavelengths), the ultraviolet radiation is also invisible, but it is very energetic and damaging (as shown by the fading of paint and our sunburned skin).

So the question is, “How can we see UV?”  Well, we can’t do so directly, but we can use a special paper having a chemical coating that’s particularly sensitive to UV.  It is the same type of paper that was used with blueprint machines using a UV lamp and ammonia fumes to copy drawings made on transparent paper.

How to Make a UV-Sensitive Box Camera:

Nature Print Paper - Educational Innovations BlogFor our box camera we’ll use a very special paper, a lens, and plain tap water, and a box.  The paper is inexpensive as is the lens, and the cardboard box is free-for-the-finding. Read the rest of this entry »

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Posted by Tami O'Connor

Eddy Current Tubes with Video

April 2, 2010

Ron Perkins, Educational Innovationsby: Ron Perkins

An eddy current is a current set up in a conductor in response to a changing magnetic field.  Lenz’s law predicts that the current moves in such a way as to create a magnetic field opposing the change; to do this in a conductor, electrons swirl in a plane perpendicular to the changing magnetic field.  Because the magnetic fields of the eddy currents oppose the magnetic field of the falling magnet; there is attraction between the two fields. Energy is converted into heat.

This principle is used in damping the oscillation of the lever arm of many mechanical balances. At the end of the arm a piece of flat aluminum is positioned to move through the magnetic field of a permanent magnet. The faster the arm oscillates, the greater the eddy currents and the greater the attraction to the permanent magnet. However, when the arm comes to rest, the attraction is negligible. Read the rest of this entry »

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Posted by Tami O'Connor

Eureka! The Archimedes Balance

March 30, 2010

Cynthia Houseby: Cynthia House

I sponsor an after school Science Club in a K-5 elementary school. The club is organized into two-week-long sessions, each session focusing on a specific topic. One of this year’s most successful sessions involved the Archimedes Balance from Educational Innovations.

Archimedes Balance Experiment 1:

  • calculators
  • answer sheet, listing the sample materials and their densities
  • fill-in table to record findings:

Students worked in pairs with first and second grade children teamed with a fourth or fifth grade student. We introduced the topic with a brief Power Point biography of Archimedes and his accomplishments, focusing on the story of King Hieron’s crown. Then students practiced determining the density of materials using the Archimedes balance and the samples supplied in the sets (all directions are included in the kit).

The Archimedes Balance relies on Archimedes’ principle which states that a floating object displaces its own weight of fluid.  The balance consists of a graduated cylinder partially filled with water and a tube that fits inside the cylinder and can float in the water.  By placing an object inside the inner tube and measuring the amount of water displaced, you can easily determine the objects weight. Read the rest of this entry »

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Posted by Tami O'Connor

The Revolution Top Floats – Why?

March 25, 2010

Marty Sagendorfby:  Martin Sagendorf

We often think we see forces.  However, in reality, we only see the results of forces.  To understand forces we must believe in Newton’s Third Law.  It states that all forces can only exist in opposite pairs and be equal in magnitude.  And… what is very interesting is that Newton’s Third Law does not stipulate that the forces be of the same kind.

Also, by Newton’s Second Law: If the (net) forces are equal, there will be no accelerations (Fnet = ma = 0)… in other words… equal and opposite (net) forces create a state of equilibrium.  An interesting example of equal and opposite (and unlike-type) forces is that exhibited by a combination of opposed magnetic fields within a gravitational (force) field.  These two different (types) of fields interact purely as ‘force fields’ – only their forces matter… not their types.

The Cosmic Magnetic Puzzle exemplifies a combination of such forces: a barbell containing two ‘donut’ magnets supported in mid-air above stationary pairs of magnets – with an additional pair of donut magnets maintaining the horizontal location of the barbell.

Read the rest of this entry »

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Posted by Tami O'Connor

Atomic Penny Vaporizer

March 25, 2010

Marty Sagendorfby: Martin Sagendorf

Imagine students’ amazement when they actually see sunlight melt a penny with the Atomic Penny Vaporizer!  This demonstration clearly illustrates the vast amount of energy illuminating the Earth’s surface.  In rough numbers: 70% of the Sun’s incident energy on our outer atmosphere is reflected back into space – only about 30% actually gets to the Earth’s surface.  But, as we experience, this is still a substantial quantity of energy.

Fortunately, this energy (I. R. – Visible – U. V.) is rather uniformly distributed over the Earth’s surface –  thus its overall intensity is such that we have a habitable environment.  However, as we all know, we can concentrate some ‘area’ of this energy to increase the ‘energy per area’ (a measure of this is the temperature of the area of concentrated energy).  A common magnifying lens (2-4 in. diameter) will concentrate sufficient energy to burn paper or other objects with a low flash point. Read the rest of this entry »

2 Comments | College level, energy, experiments, High School level, Middle School level, Physics | Tagged: , , , , , , , , | Permalink
Posted by Tami O'Connor

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