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Phys 313 Quiz 9

Question 1

Electric field is E = (3, 0, 0) N/C everywhere. What is the potential difference V(B) - V(A) if

      A  =  (1, 1, 1) m
      B  =  (2, 2, 2) m

   Answer:  To find the potential difference, integrate the electric
            field over a path from A to B:

                                    B
                                   / 
               V(B) - V(A)  =   -  |  E dot ds
                                   /
                                  A

            Recall that 3 N/C = 3 V/m.

                                             
                            =   -     E * x    evalulated from A to B

                            =   -  [ (3 V/m * 2 m) - (3 V/m * 1 m) ]

                            =   -  [   6 V/m       -      3 V/m    ]

                            =   -  3 Volts

Question 2

Electric potential is V = 6 Volts everywhere. What is the electric field at point A = (1, 1, 1) m?


   Answer:    Electric field is gradient of electric potential

                 Ex  =  dV/dx  =  0 

                 Ey  =  dV/dy  =  0 

                 Ez  =  dV/dz  =  0 

Question 3

Electric field of strength 6 N/C can be written equivalently as ...

   Answer:  6 V/m, because 1 Newton/Coulomb is the same as 1 Volt/meter

Creative Commons License Copyright © Michael Richmond. This work is licensed under a Creative Commons License.