# Exam 1, PHYS 202 Name________________________ Chapters 21, 22, &amp; 24

```Exam 1, PHYS 202
Chapters 21, 22, &amp; 24
8 February 2006
Name________________________
1) The charges and coordinates of two charged particles held fixed in an x-y plane
are q1=+2.0 &micro;C, x1=3.5 cm, y1=0.5 cm, and q2=-3.0 &micro;C, x2=-2.0 cm, and y2=1.5
cm. Find (a) the magnitude and (b) the direction of the electrostatic force on
particle 2 due to particle 1.
2) A non-conducting spherical shell, with an inner radius of 4.0 cm and an outer
radius of 7 cm, has charge spread nonuniformly through its volume between its
inner and outer surfaces. The volume charge density is the charge per unit
volume (C/m3). For this shell, ρ=b/r where b=5.0 &micro;C/m2. What is the net charge
on the shell?
3) In this figure, the four particles form a square of edge length a=3.0 cm and have
charges q1=+10 nC, q2=-20 nC, q3=+30 nC, and q4= -40 nC. In unit vector
notation, what net electric field do the particles produce at the square’s center?
4) An alpha particle (the nucleus of a helium atom) has a mass of 6.64&times;10-27 kg and
a charge of +2e (the charge of an electron is 1.6&times;10-19 C). What are the (a)
magnitude and (b) direction of the electric field that will balance the gravitational
force on the particle?
5) What is the magnitude of the electric field at the point (2.0 i + 3.0 j - 4.0 k) meters
if the electric potential is given by V = 2.0 xy 3 z 2 , where V is in volts and x, y, and
z are in meters?
6) How much work is required to set up the arrangement of this arrangement of
particles if q=2.30&times;10-12 C, a=64 cm, and the particles are initially infinitely far
away and at rest?
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