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. m_e=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____________