Tuesday, October 21, 2008
Energy Conversion Gone Wild
The Physics Level 1 experiment for Chapter 10 in the Laboratory Workbook is an imaginative way to engage students in using the knowledge they have gained throughout the physics curriculum. Students are led through the process of naming all the forms of energy they have studied and then creating a “chain reaction” in which two or more forms of energy are converted to another form.
The Workbook helps students narrow their ideas down to those that are practical for an at-home experiment. But what if students could design an experiment without the limits of practicality? Let’s let them use their critical thinking skills and accumulated knowledge without limitations.
I. Prepare the lab notebook
As students develop their “wildest imagination” experiment, they will need space for a new Objective and Hypothesis. And they will need plenty of space to plan their imaginary experiment, draw its components and steps, and record their conclusions.
II. Energy conversions without limits
Have students look again at their Workbook list of the forms of energy studied and review their list of ways to represent every form of energy. They should then add to it without regard to whether they could actually find and use the materials necessary. Which forms did they not use in the practical experiment they designed? This new “no-limits” experiment should include those forms. Or, can they create an experiment to represent every form of energy converting to another in one grand experiment?
Students should have fun creating an imaginative sequence of energy conversion, but help them to think about whether each step could actually work if they had all the time, money and resources necessary to perform their experiment. They should draw or write out every step they envision.
III. What happened?
Students obviously cannot observe their “impractical” experiment directly, but using their descriptions or drawings of the experiment, have them write what the results of each step might be. Allowing them to use their knowledge without regard to practical application encourages both imaginative thinking and also critical thinking skills.
Feel free to write to us with information about how the experiment variations and expansions are received by your students. We appreciate all feedback.
Posted by Rebecca W. Keller on 10/21 at 02:43 PM
Monday, October 13, 2008
Waves of Light
Chapter 9 in the Physics Level 1 Laboratory Workbook describes experiments in which students can observe the wave nature of both light and sound. The variation presented here expands the portion of the experiment with light waves. A third prism is introduced to see how it affects the separation of light waves.
I. Prepare the lab notebook
Have students create an Objective and Hypothesis for what might happen when a third prism is added to the two prism lined up with the flashlight. They will want to look at the Results they recorded for the original experiment to make a new Hypothesis. For example, they should have observed that the order of colors in the rainbow created by the second prism was the “inverse” of the color bands produced from the first prism. Students will want to have plenty of room in their notebook to draw the placement of the prisms and the resulting bands of light. They may want to record written descriptions of what they observed as well, including notes on how the prism angles were adjusted to get results.
II. Setting up the prisms
The flashlight and first two prisms should be set up as shown in the Lab Workbook. Students will want to make any adjustments that had been necessary to create the second, inverse rainbow. Now, have students add a third prism at the end of the first two. They should observe how results differ when the various sides of the third prism are facing the flashlight.
III. What happened?
Students should draw the set-ups they created and the results of each set-up. Have them describe what changed to get varying results. We invite you or your students to send us the results observed, along with any notes about the difficulty or ease of achieving visible light waves with the third prism.
Feel free to write to us with information about how the experiment variations and expansions are received by your students. We appreciate all feedback.
Posted by Rebecca W. Keller on 10/13 at 08:59 PM
Wednesday, October 08, 2008
Magnetic Electricity
Chapter 8 in the Physics Level 1 Laboratory Workbook is an experiment that walks students through building an electromagnet. They demonstrate for themselves that increasing the electrical current or increasing the number of loops in the coil will increase the strength of the magnet. But Chapter 8 also discusses that magnets, along with a wrapped wire coil, can be used to induce electric current. Let’s help the students demonstrate how this works by building a simple generator.
I. Prepare the lab notebook
Have students create an Objective and Hypothesis for this experiment. They may want to state whether spinning magnets inside of a heavily coiled wire (the solenoid) will produce an electrical current sufficient to make a light bulb glow.
II. Building a simple generator
The materials needed for this experiment are: a toilet paper tube, a minimum of 100-150 feet of copper wire (copper craft wire is fine), a nail longer than the paper tube, two magnets that can be taped to the nail, electrical tape, and a light bulb.
Wrap the copper wire around the outside of the paper tube a few hundred times to create a strong coil. Make certain the ends of the tube are not obstructed. Leave enough wire on each end of the coil so that the ends can soon be attached to the light bulb. Attach the two magnets, one on either side of the nail. Place the nail with magnets inside the tube so that the magnets can be spun freely. Attach the loose ends of the wire coil to the light bulb. One wire end should be taped to the bottom of the bulb and
the other should be taped to the metal side. Now let the students spin the magnets inside the tube and watch to see if the light bulb glows.
III. What happened?
Students will want to record their observations, including whether the speed of the spinning magnets makes a difference in the brightness of the light produced.
Feel free to write to us with information about how the experiment variations and expansions are received by your students. We appreciate all feedback.
Posted by Rebecca W. Keller on 10/08 at 08:03 AM
Monday, September 29, 2008
Challenge Variation: Calculating Current
In the Physics Level 1 Laboratory Workbook, Chapter 7’s experiment allows students to observe and record the effects of insulators and resistors on electrical current and the heat produced by the current. The experiment actually demonstrates “Ohm’s Law” even though the text does not refer to it that way. This variation is called a Challenge Variation, because students can use their original experiment and the formula for Ohm’s Law to uncover new information.
I. Prepare the lab notebook
Have students record the formula for Ohm’s Law (V=IR) in their notebook. They will want to write that V is the voltage, I is the current, and R is the resistance (resistance is measured in units called ohms).
II. Calculating the Current
Students could not measure the current in their Wookbook experiment, because they did not have their system hooked up to an amp meter. Can they still determine the current that flowed?
Using the equation V=IR, it is possible. Another way to write this equation is I=V/R (current equals voltage divided by resistance). The formula shows that when resistance goes up, the current goes down (I is inversely proportional to R).
So students can estimate the value of the current (I) by using the known value of the resistors (R) and the known value of the 1.5V battery (V).
III. What should the formula yield?
The students’ formula should look like this:
I (unknown current) = V (1.5V) divided by R (known ohms of the resistors used)
Feel free to write to us with information about how the experiment variations and expansions are received by your students. We appreciate all feedback.
Posted by Rebecca W. Keller on 09/29 at 09:43 PM
Monday, September 22, 2008
Electrical Energy: Charging the Electroscope
The Chapter 6 Laboratory Workbook experiment for Physics Level I guides students through the process of building a simple electroscope and testing a few materials to create an electric charge. Let’s continue to make use of the fascinating little machine and allow students to learn more about which materials create the most charge.
I. Prepare the lab notebook
Students will want to create a quick table listing new materials to be tested and a space to record what happens to the strips of aluminum in the electroscope as each new material is tested. Was there enough data in the results of their first experiments for them to make more detailed hypotheses about each new category of material to be tested? Can they make a hypothesis about whether all materials in the same category will produce similar results?
II. Static electricity from various materials
Have students gather or locate a few samples of materials in categories such as cloth (cotton, wool, polyester or nylon), metal (copper, iron, or steel), or paper and plastic (plastic wrap, paper towels, gift wrap tissue paper, facial tissues). Students may also wish to vary the “rod” that is used to rub various materials in an effort to produce electricity. For example, if a plastic comb had been used, students may want to record the results of using that comb with these new materials and then repeat those experiments using a metal or plastic measuring spoon. Are results different when the “rod” is changed?
III. What happened?
Discuss with students their observations about which materials created the strongest separation of the aluminum strips and which made the least. Remind students that an object (the rod) is being charged because electrons are being moved from the source material.
Feel free to write to us with information about how the experiment variations and expansions are received by your students. We appreciate all feedback.
Posted by Rebecca W. Keller on 09/22 at 11:16 AM
