Learning About Light

MARTY SAGENDORFby: Marty Sagendorf

Light is magic stuff: it has no mass, it comes in many colors, it has energy, it can be emitted and absorbed, but it can’t be saved in a bottle or bucket.  Even though we can’t ‘save’ it, we can explore the many ways that light behaves around us.  We are told, or we read, about reflection, refraction, and the many other properties of light’s interaction with objects, but until we actually experience these we really don’t fully appreciate ‘the magic of light’.

Let’s start learning about light!

That’s what this Optics Kit, from Educational Innovations, allows us to do – experience light by doing.  This kit provides the necessary components to perform extensive investigations – ten are completely detailed – and new ideas for experimentation will naturally develop as optics principles become familiar.


Let’s begin with something we see every day:


Start by drawing a line along, and one-half inch from, the long side of a piece of 8-1/2”x11” white paper.  At the mid-point of this line, draw a perpendicular line extending across the paper.  This line represents a ‘NORMAL’ to the mirror’s surface.

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Making Optics Demos Easier

Martin Sagendorfby:  Martin Sagendorf

We’ve all likely encountered the time-consuming effort required to set up an optics demo; all the necessary components are on hand, but they don’t easily work together.  The difficulty is obvious: the various components are either ‘loose’ or mounted at differing heights.  Thus: wasted and frustrating time ‘shimming’ with books and pads to match the heights of the components.

The solution is simple: choose a height (above bench top) and mount every optical component at the same (optical centerline) height.  But, how does one choose a height?  Simple: first, determine the optical component with the highest centerline then second, build supports for all the other components – matching this centerline height.

I began with a 100 Watt clear light bulb mounted upon a wooden base – the center of the filament was 4-3/4” above the bench top.  I then ensured that everything else I had, or planned to incorporate in demos, could be centered at this height.

Optics Demo

The supports shown in the following illustrations are of ¾” pine – either screwed or glued together.  Where required, various combinations of rubber feet and jackscrews provide support and positioning capability.  When applicable, stacks of steel washers are incorporated to add stability. Read the rest of this entry »