Coulomb s Law Mini-Lab

Transcription

1 Setup Name Per Date Coulomb s Law Mini-Lab On a fresh piece of notebook paper, write the above title, name, date, and period. Be sure to put all headings, Roman numerals and regular numbers on your paper. You do not need to write any questions unless directed to do so. On your computer, go to Unit 7.18 in Weber Online and open all the resource files (the simulation will only open on Windows computers running Java; the Logger Pro file will only run if your computer has Logger Pro installed). BE SURE TO SAVE THE LOGGER PRO FILE IN THE DOCUMENTS FOLDER IN YOUR COMPUTER OR YOU WILL HAVE TO START THE ENTIRE LAB OVER AGAIN!!! In the simulation, in the green box on the bottom right, check the boxes for grid, Show numbers, and tape measure. In the simulation file, you should see now this: Objective Your job in this lab will be to find out how the electric force changes when charge or distance changes. How to Do Your Job In this simulation, you can move the measuring tape and the charges around, so you can measure the distance between their centers. You can also change the amount of charge simply by piling more charges on top of each other. BE WARNED: IF YOU PILE POSITIVE AND NEGATIVE CHARGES TOGETHER, THEY WILL CANCEL AND RUIN YOUR LAB DATA!

2 Data Collection Part 1: The Effect of Charge I. DO NOT draw the table below on your own paper; you will keep your data in Logger Pro for this lab. In the following steps (not yet), you will be finding the electric force by changing the charges. Initial by the I on your paper that you have read this: Click the button on the bottom right of the simulation. For each Charge 1 shown in the table at right: A. In the simulation, add charges shown in the blue Charge 1 column at right (see the picture below). B. In the simulation, place an orange E-Field Sensor 1.5 m to the right of the charge: see picture below, use tape measure (DO NOT move the charges around yet). C. In Logger Pro, in the Part 1: Charge 1 vs. Electrostatic Force table, RECORD the force value that the simulation gives you. Leave the other table for Part 2 of the experiment. For this experiment, a force arrow facing right will be positive, left will be negative.

3 Analysis Questions Part 1 1. You started out with 1 nc for Charge 1. What happened to the electric force when you doubled that to 2 nc? (doubled, 4 times bigger, half, one-fourth) 2. What happened to the electric force when you made the 1 nc charge four times bigger, up to 4 nc? (doubled, 4 times bigger, half, one-fourth) 3. In Logger Pro, is your Charge 1 vs. Electrostatic Force graph a straight line or a curve? 4. In Logger Pro, looking at the Charge 1 vs. Electrostatic Force graph, how much bigger would the electric force be if you made the 4 nc charge five times bigger, to 20 nc? II. Show Mr. Ward your data table and graph (in Logger Pro) and ask him to stamp by the II on your paper. Part 2: Effect of Distance Click the button on the bottom right of the simulation. In the simulation, place one positive charge on the far left (see picture below). Move the measuring tape so that the zero mark is on the far left (see picture below). Also move an orange E-Field Sensor so that its center is at the 0.5 meter mark on the measuring tape. Your screen should now look like the following picture.

4 III. DO NOT draw the table below on your own paper; you will keep your data in Logger Pro for this lab. In the following steps (not yet), you will be finding the electric force by moving the orange E- Field Sensor. Initial by the III on your paper that you have read this: For each distance shown on the table at right: A. In the simulation, move the orange E- Field Sensor to the distance listed in black on the following table. (DO NOT change the charges). B. In Logger Pro, fill in the matching table with the force values that the simulation gives you. IV. Show Mr. Ward your data table and graph (in Logger Pro) and ask him to stamp by the IV on your paper. Analysis Questions Part 2 5. You started out at 0.5 m. When you doubled the distance between charges from 0.5 m to 1 m, the force dropped. To find out what fraction of the original force you had left, use the following equation, and show your answer AS A FRACTION. SHOW YOUR WORK ON YOUR PAPER!!! (HINT: divide the electric force at 1 m by the electric force at 0.5 m and display it as a fraction in the calculator.) Force _ at _1m Fraction _ of Force _ at _ 0.5m _ Original _ Force Your numbers:... Mr. Ward s Stamp 6. When you tripled (multiplied by three) the distance between charges from 0.5 m to 1.5 m, the force dropped. To find out what fraction of the original force you had left, use the following equation, and show your answer AS A FRACTION. SHOW YOUR WORK ON YOUR PAPER!!! (HINT: divide the electric force at 1.5 m by the electric force at 0.5 m and display it as a fraction in the calculator.) Force _ at _1.5m Fraction _ of Force _ at _ 0.5m _ Original _ Force Your numbers:... Mr. Ward s Stamp

5 7. In Logger Pro, is your Distance vs. Electrostatic Force graph a straight line or a curve? 8. In Logger Pro, looking at the Distance vs. Electrostatic Force graph, what do you suppose would happen to the electrostatic force if you kept making the distance greater and greater? Conclusion 9. When charge doubled, a. electrostatic force. b. This is called. 10. When distance doubled, a. electrostatic force. b. This is called.