An effective approach to online physics by incorporating home based

experiments

Wednesday, May 11th, 2005

Hamilton Club

Presented by:

Prof. Mike Mikhaiel

Science Department

INTRODUCTION

In the area of education, online environments of learning now exist and are increasing at an exciting rate. Such environment offer great potential and huge possibilities of education especially in the United States and the Western world.

Online learning is used to deliver courses of various disciplines. However, their potential may only be realized if teachers can accommodate their personal theories, beliefs, and practices to suit the characteristics of the new environment.

Online learning is not just a matter of gathering notes and presenting it online but instead, new ways have to be defined, to evolve and adapt to the new environment.

The task of offering science subjects online is very difficult to deliver especially when experiments are a crucial part of the evaluation process. Interactive virtual activity and simulations have been developed and used to replace them and some educators have endorsed this method while others have not.

The question remains: are virtual experiments comparable with traditional experiments?

ANSWER The answer to this question is yes.

QUESTION

SOLUTION

• I devised a method where students can actually perform experiments similar to what they would do in traditional methods.

• The experiments may be different but the concepts, procedures, and the end results are the same.

NEW EXPERIMENTS

The new experiments are experiments that can be done at home or everywhere using materials found everyday in a dollar store and in most cases at home.

EXPERIMENT 1Measuring the speed of light with chocolate

and a microwave.• Equipments: A microwave, a ruler and chocolate, cheese or any other food that

melts.• Procedure: 1. Remove the turntable from the microwave and replace with chocolate on the

surface. 2. Heat until the chocolate just starts to melt. 3. There will be some melted hot spots and some cold solid spots in the chocolate.• Measurements: measure the distance between the hot spots.• Analyze: The distance between the hot spots is half the wavelength of the

microwave.• Calculations: Now you are ready to find the speed of light. Find the frequency of the microwave by reading the printed frequency on the back

of the microwave. The speed of light is equal to the wavelength multiplied by the frequency of the

microwave.

EXPERIMENT 1 EXPLANATION

When you turn on your microwave oven, electrical circuits inside start generating microwaves- electromagnetic waves with frequencies around 2.5 gigahertz-2500000000 Hz. These waves bounce back and forth between the walls of the oven, the size of which is chosen so that the peaks and troughs of the reflected waves line up with the incoming waves and form a “standing wave”.

EXPERIMENT 1 EXPLANATION (CONT.)

• The wave forming inside the microwave is a standing wave with half the wavelength. This wave has nodes and antinodes. Nodes will give you minimum vibrations and you see part of the chocolate is cold and antinodes will give you maximum vibrations and you see the chocolate is melting in this area.

• you will find the speed of light (C) by using the equation C = .

EXPERIMENT 2How to tell a diamond from a cubic zirconia

Background information: The cubic zirconia is a reasonably good “fake” diamond- although calling it a fake diamond is perhaps a little unfair- the cubic zirconia is a gemstone in it own right, referring to it as a fake diamond makes it sound like the glass “stones” used in costume jewelry. The reason that it is possible for a cubic zirconia to pass as diamond to casual or untrained scrutiny is that the cubic has many of the properties of a diamond-they are the same shape and color. However, there is one important property of diamonds that a cubic cannot mimic well- the “sparkle.”

Theory: Diamonds have a very high refractive index- this means that light entering or leaving a diamond will be bent strongly as it crosses the diamond-air interface. The amount of bending is given by Snell’s Law:

Sin 1/Sin 2 = n1/n2

Thus, we can see that when light travels from diamond (n for diamond is 2.42) to air (n for air is 1) the sine of the angle made by the beam of light in the air is greater than the angle made in the diamond.

• Further, you can see that the, above some critical angle of incidence, the “sin(theta in air)” given by Snell’s Law will be greater than 1.

• As this is impossible, we know that above the critical angle, we cannot have refraction. But the light has to go somewhere- it is reflected back into the diamond.

• In a cubic zirconia, the refractive index is smaller (n for zirconia is 2.14) so the critical angle in the cubic is greater.

Experiment: We see the clear gemstones in the air because of the light that reflects off their faces. The amount of reflection is related to the difference in refractive index between the gemstone and air. In this situation, the cubic and the diamond reflect a very similar amount of light. But, if you submerge the gemstones in water, the ratio of the refractive index differences increases markedly.

Thus, if you submerge a cubic zirconia in a glass of water, the gemstone virtually disappears, while a diamond is still easily visible.

• To be continued……………….