PRACTICE QUIZ 20A

Answer the following questions completely and clearly.

1. What must be true about the electrons and protons in a charged object?

  

2. How does a balloon become charged when it is rubbed against hair?

 

3. Who first used the words "positive" and "negative" to describe charge? How were the original uses of these terms misleading?

  

 

4. A sock was given an electric charge as it tumbled in the clothes dryer. How might someone determine whether the sock is positive or negative?

  

  

5. How does an insulator differ from a conductor?

  

  

6. What is the law of conservation of charge?

  

 7. Describe the operation of a laser printer.

 

 

 

8. Tell how an object can be charged by conduction.

 

 

 9. Tell how an object can be charged by induction.

 

 

10. Write the equation for Coulomb's law.

 

Solve the following. Show all work and circle your answer.

11. Three charges, q₁, q₂, and q₃, lie along the x-axis at x = 0, x = 3.0 cm, and x = 5.0 cm, respectively. Calculate the electric force on each of the three charges when q₁ = +6.0 mC, q₂ = +1.5 mC, and q₃ = -2.0 mC. (Remember that 1.0 mC = 1.0 x 10^-6 C.)