Mastering Physics: PhET Tutorial: Charges and Electric Potential

Mastering Physics: PhET Tutorial: Charges and Electric Potential

Part A

Question: Using the voltage meter, you should find that 1 m away from the charge, the voltage is 9 V.  What is the voltage 2 m away from the charge?

Answer: 4.5 V 

Part B

Question: What is the voltage 3 m away from the charge?

Answer:  3 V

Part C

Question: Place several E-Field Sensors at a few points on different equipotential lines, and look at the relationship between the electric field and the equipotential lines. Which statement is true?

Answer: At any point, the electric field is perpendicular to the equipotential line at that point, and it is directed toward lines of lower voltages.

Part D

Question: Equipotential lines are usually shown in a manner similar to topographical contour lines, in which the difference in the value of consecutive lines is constant. Clear the equipotential lines using the Clear button on the voltage tool. Place the first equipotential line 1 m away from the charge. It should have a value of roughly 9 V. Now, produce several additional equipotential lines, increasing and decreasing by an interval of 3 V (e.g., one  with 12 V, one with 15 V, and one with 6 V). Don’t worry about getting these exact values. You can be off by a few tenths of a volt.Which statement best describes the distribution of the equipotential lines?

Answer:  The equipotential lines are closer together in regions where the electric field is stronger.

Part E

Question: Now, remove the positive charge by dragging it back to the basket, and drag one negative charge toward the middle of the screen. Determine how the voltage is different from that of the positive charge.How does the voltage differ from that of the positive charge?

Answer: The voltages become negative instead of positive and keep the same magnitudes.

Part F

Question: What is the voltage at the midpoint of the two charges?

Answer: Exactly twice the voltage produced by only one of the charges at the same point

Part G

Question: What is the voltage at the midpoint of the dipole?

Answer: The voltage at the midpoint of the dipole is zero.

Part H

Question: Try to have the equipotential lines equally spaced in voltage. Then, use an E-Field Sensor to measure the electric field at a few points while looking at the relationship between the electric field and the equipotential lines.Which of the following statements is true?

Answer: The electric field strength is greatest where the equipotential lines are very close to each other.