Summary

• Winter Break

• Syllabus overview
  • books & supplies
  • course goals
  • assignments & grading
  • WebAssign
  • Personal Response System
  
  
• About the professor
  
  
• How to learn physics
  
  • learning athletics
  • learning music
  • interactive lectures
  
  
  
• Electric charges
  • origin & types
  • conductors
  • insulators
  • the electroscope
  • electrical ground
    Example #1
    
  • electrons & protons, Coulombs
  • conservation of charge
    Example #2
    
    Example #3
    
  
  
  
• How to succeed in college
  • Set a GPA goal
  • Treat college like an 8 to 5 job
  • Attend class
  • Keep up
  • Relate to your professors
  • Be a "well-rounded square"

kw4
Could you use fur, silk, or wool to negatively charge a metal rod that is held in your hand?
A. fur      B. silk      C. wool
D. None of these
Answer







kw4
When a neutral water molecule disassociates into an H⁺ ion and an OH^- ion, what can we say about the sizes of the charges on the two ions?
A. They are the same size.
B. The OH^- has more neg. charge
C. The H⁺ has more pos. charge
D. Need to measure the charges.
Answer







klm
If silk is used to charge a glass rod, is the charge on the silk positive or negative?
A. positive            B. negative
C. The silk is neutral.
Answer







 



D. None of these
The metal would conduct any excess charges to your body, which would act as an effective ground so that no excess charge would remain on the metal rod.












 



A. They are the same size.
This must be true because the sum of the two charges must be zero in order for the molecule to have been electrically neutral before it disassociated.












 



B. negative
By definition silk rubbed on glass produces a positive charge on the glass. That means electrons were removed from the glass and are now sticking onto the silk, giving the silk a net negative charge.