Monday 7 Feb:

 

Target: Review of Ch 15-18 Electricity/Currents

 

1. Quiz Equations

 

2. Test Ch 15-18 Thurs/Fri (10 -11 Feb)

 

 

Quiz Equations (Electricity/Current):

 

     Description:                                              Equation:

1. Electric Force:        F       =

 

   or   F =   kq1q2 / r2

2/3. Electric Field:         E      = 

(Two Equations)

 E = k q1 / r2    or

4. Electric Field:         E      = 

Note: (voltage & distance)

 
   

6. Capacitance            C      =

Note: (Charge & voltage)

 

 

7. Capacitance            C      =

Note: (parallel plate capacitor)

 

8/9. Potential energy stored in a charged capacitor:      (Two Equations)

     Uc =

 

10. Resistance & Resistivity:   

                                       R  =

 

11. Ohm’s Law:

 

12/13/14

Electrical Power (electrical circuit):                        P   =

   or     or   V2/R

15. Capacitors in Series:   Cs  =

Cs =  (C1) (C2)  / (C1) + (C2) or

 

16. Capacitors in Parallel:  Cp =

Cp =∑i Ci

17. Resistors in Series:   Rs  =

 

18. Resistors in Parallel:  Rp =

Rp = (R1)(R2)/(R1)+(R2)or   

19. Elect Potential (with Elect Field):

                                     V =

 V = E d   

  20. Coulomb Constant:  k =

 K= 1 / 4peo

 

 

 

 

 

 

 

 

 

                R1 = 4.0 W                 I2

 

 

                        

 

                             R3 = 9.0 W  

6.0V                                                       18V

 

            I1                     I3

 

Find a. I3     b. I1   c. I2

 

a. I3 = 18V / 9.0 W    = 2.0A (CCW, i.e. top to bottom)

 

b. starting from lower left corner (CW):

      6V + I1(4.0 W) -18V = 0

       I1(4.0 W) = 12V

       I1          = -3A  (CW)  or 3A (CCW)

 

 

 

c.  Junction on top (out of  I2  ) 

                I2  = I3 (CCW)+ I2 (CCW)

                I2  =  2.0A  + 3A = 5A

 

 

                     V1                 V2

                     

                      12.0 mF      8.0 mF

 

                  28.0V                             10 W  

                               

 

 

 

 

Find:    a. V1                 b. V2

given:   V1 + V2   =  28V  (Fully charged capacitors)

 

*Note: When capacitors are in series, the charge (Q) on each capacitor is equal.  (Q = CV)

 

 

 

a.    V1 + V2   =  28V

     C1V1  =  C2V2 

 

 V1  + (C1V1 / C2) = 28V

 

 V1  + (12 x 10-6)V1 / (8 x 10-6)  = 28V

    2.5V1 = 28V

          V1 = 11.2V

b. V1 + V2   =  28V

    11.2 + V2   =  28V

     V2   =  16.8V