Physics II (PHY-1203) Laboratory Experiment 1 “Coulomb’s Law”
Purpose: The purpose of this experiment is to analyze the relationship among force, charge and distance summarized in Coulomb's law.
Theory:
The first law of electrostatics states that like charges repel and unlike charges attract.
Freeware Simulation Package: The ejs_electric_sampler shows the force vectors on charges. Students can move and change the value of an individual charge and add more charges.
Procedure & Data: 1. Run the simulation file. 2. Double click (Coulomb Force) on the left-hand side. 3. Move the red and green charges around and note what happens to the force arrows and the force. Do these particles have the same charge or opposite charge? Yes How can you tell? As Coulomb’s law tell the charges have the same signal repel and unlike charges attract each other.
Mohamad Muflehi
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4. Reset the simulation. Both the red and green charges have the same magnitude (charge). How does the force on the red charge compare to the force on the green charge? The Two charges have the same effect if the “Q” and the “F” in red charge in increase and the green charge will have the same magnitude. 5. Now, use the red slider to increase the red charge. What happens to the force on the red charge? Increase and both charge will have same force. What happens to the force on the green charge? Increase and both charge will have same force. 6. Take a screenprint of your configuration and paste it here.
7. Which charge experiences the largest force? The both charge have the same force. 8. Set the red charge back to q=1. Change the size of the green charge, what happens to the force? Why? The Force will change, because in Coulomb’s law if one of the Q change the Force will change.
Mohamad Muflehi
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Since the force is a vector, if you add a third charge, you should be able to arrange the charges so that the force on one of the charges is zero (no arrow) while the force on the other two charges is non-zero. 9. Reset the simulation and add another charge. Move the charges around until the red charge has no force on it. Take a screenprint of your configuration and paste it here.
10. In this configuration, if you increase the charge of the red charge, will it experience a force? The force of the blue and green charge will increase, but The force of re d charge will still Zero. 11. What if you change the green or blue charge, will the force on the red charge remain zero? No will not remain zero. If we change one of green or blue charge, the force of red charge will increase, and all charges will have different force If we want to to make the red charge force remain zero than we should make green and blue charge have the same force.
Mohamad Muflehi
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12. Add another charge and keep the force on the red charge at zero. Take a screenprint of your configuration and paste it here:
Evaluation and Review Questions: 1. State the first law of electrostatic. Charge particles repel each other and unlike charge particles attract each other.
2. State Coulomb’s Law. Coulomb's law gives the electric force acting between two point charges. 3. Write the mathematical formula for Coulomb’s Law.
4. What is the direction of the Coulomb force? The direction of the electric force exerted on one point charge due to another point charge is always along the line that joins the two point charges 5. What is the value of the proportionality constant? K=9x109 N.m2 /c2
Mohamad Muflehi
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6. Two point charges initially attract each other with a force of 750 N. if their separation doubled, what is the new force of attraction?
7. A +60 µC charge is placed 60 mm to the left of a +20 µC charge. What is the resultant force on a -35 µC charge midway between the two charges?
60mm +60 C
q1
+20 µC
q2
Abstract: This experiment about Coulomb’s law, we use a program Freeware Simulation Package, it shows the force vectors on charges and can move and change the value of an individual charge and add more charges. From the experiment, we prove the relationship among force, charge, and distance summarized in Coulomb's law, which is the first law of electrostatics states that like charges repel and unlike charges attract.
References: College Physics .Giambattista, A. Richardson, R. C. Richardson, B. ( 1 2 3 4 5 6 7 8 9 0 DOW/DOW 1 0 9 8 7 6 5 4 3 2) , 4 ed.
