University Physics-PHYS 221, Fall 2000, UT Martin

Quiz 2 (Electric Field)-Redo Quiz

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Constants: e= 1.60x10-19C, k = 9.0x109 N.m2/C2. me=9.11x10-31 kg.

1)     

 
The figure below depicts three of the electric field

lines in some part of the space. What is the direction of the force

on a positive test charge placed at points A and B on the field line?

Draw an arrow at points A and B to respond! Indicate

how you decided on the direction!

 

 

 

 

 

2)      In the picture for problem 1 above, the field strength in the

region to the left of point B is ____________that of the region to the right of point B.(Choices: greater than, smaller than , equal to).

 

 

 
 


3) An arrangement of two point-like charges

,as shown in the picture, sets up electric field

in the surrounding region. At which point,

the total electric field is most likely to be zero?

 

a) A b)B c)C d)D

 

 

 

3)      a) What is the magnitude of a uniform electric field that accelerates an electron at a rate of 1.0x1018 m/s2. Assume that the electron is initially at rest when it is released from the midpoint of two equally and oppositely charged parallel plates?

 

 
Answer_______________

 

 

 

 

 

b) Which direction does the electron move?

 

Answer___________

 

 

 

c) What is the sign of the charge on the upper plate?

 

Answer____________

 

 

 

 

 

 

 

 

4)      A thin glass rod is bent into a semicircle of radius.

 
A charge +q is uniformly distributed along the upper

half, and a charge q is uniformly distributed

along the lower half as shown. Draw

the direction of the electric field at the center of

the semicircle.

 

 

 

 

 

5)      An electric field dipole consists of charges +2C at x=2 cm and 2C at x= -2 cm.

 

a)     

 
What is the electric dipole of the system?

 

Magnitude_____________Direction_________

 

 

 

 

 

 

 

b)      If a uniform electric field of 10 N/C is applied along the +y direction, what is the potential energy of the dipole in the external field?

 

Answer____________