PhysicsLAB Worksheet
Electric Field Drill: Point Charges

1. How is the direction of an electric field line defined?
 

 
2. Is the central "parent" charge in this diagram positive or negative? Look CAREFULLY to "see" the arrows!
 
3. Are the charges shown equal in magnitude?  Do they have the same sign?
 
      
 
 

4. What does it mean to say that an electric field is "radial?" 

5. If the field lines in an electric field are parallel to each other, what does this tell you about the electric field strength in that region? 

6. What does an electric field look like between two charges of opposite sign?
 
7. Which arrow represents the direction of the electric field at point P due to the stationary charges +Q and -Q?
 
8. What does an electric field look like between two charges of the same sign?
 
9. Which of the four field patterns shown represents a possible electrostatic field?
 
Refer to the following information for the next five questions.

In the following diagram, B is twice the distance from the central charge as is A. C is three times the distance from the central charge as is A.
10. How do the field strengths compare at points A and B? 

11. How do the field strengths compare at points B and C? 

12. If the central charge is +3 µC, and point B is 2 meters away, what is the magnitude of the electric field strength at point B? 

13. What magnitude force would an electron placed at point B experience? 

14. Would a free proton placed at point B naturally move towards A or towards C?
 
Refer to the following information for the next four questions.

Refer to the following diagram in each of the questions in this set.
 
15. If each charge group is temporarily connected with a conducting wire, then in which system will the residual charge on each sphere be + ½q?
 
16. The electric field intensity is zero at the midpoint of which group of charges?
 
17. In which group of charges is the attractive force at the midpoint the greatest? Let the distance between each set of charges be 2r.
 
18. Three identical metal balls are mounted on insulated rods. Ball A has a charge of +q, while balls B and C are uncharged. Ball A is brought into contact momentarily with ball B, and then with ball C. At the end of this experiment, how much charge does each ball have? 





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