1] Below is a diagram showing the relative
positions
of 3 charges. Determine the force on the
 5 µC charge
due to the other 2 charges. [ remember you need magnitude &
direction
]
10 cm
+ 8 µC ·

·+
2 µC

 5.0 cm

 5 µC ·
Answer: 57 N @ 62 degrees
above x axis
2] In the hydrogen atom a single electron
orbits
around a single proton. The smallest electron
orbit has a radius of 5.29
x 10^{11 }m. How much work is required to completely
remove
the
electron from this orbit
( i.e., move the electron to infinity where
we
take the electric potential to
be zero)
Answer: +4.3 x 10^{18}
J
3] {A} Determine the electric field at the
point
labeled, x, in the figure below.
[ remember magnitude & direction ]
+ 2 µC
·  x
10 cm
Answer: 1.8 x 10^{+6}
N/C pointing to right
{B} A charge that is now
placed at point x above experiences a force of 1.8 N that is directed
toward the + 2 µC charge. What is the magnitude and sign
of
the charge placed at point x?
Answer: 1.0 x 10^{6}
C
4] {A} The cross sectional area of a
parallel
plate capacitor is 6.25 cm^{2} . The plates are separated
by a distance of 4.00 mm with only air between them. What is the
capacitance
of this
capacitor?
Answer: 1.38 x 10^{12} F
{B} Explain what a capacitor does and how it does it.
Answer: see your text
7] The cross sectional area of a
parallel plate
capacitor is 6.25 cm^{2} . The plates are separated
by a distance of 4.00 mm
with only air between them. If the work done on a +4.0 m
C in
moving it from one plate
to the other is 2.0 x 10^{4} J , what is the total charge, Q,
on the
capacitor?
Answer: 7.0 x 10^{11}
C
MULTIPLE CHOICE
1 ] Which of the following is not a vector?
a. electric force
b. electric field
c. electric charge
d. electric lines of force
e. acceleration
2] If a conductor is in electrostatic equilibrium near
an electric charge
a. the total charge on the
conductor must be zero
b. any charge on the conductor
must be uniformly distributed
c. the force between the
conductor and the charge must be zero
d. the total electric field of
the conductor must be zero
e. the electric field of the
conductor is perpendicular to the surface
3] For an electron moving in a direction opposite to the
electric field
a. its potential energy increases and
its electric potential increases
b. its potential energy decreases and
its electric potential increases
c. its potential energy increases and
its electric potential decreases
d. its potential energy decreases and
its electric potential decreases
e. both the potential energy and the
electric potential remain constant
ANSWERS;
1] c
2] e
3] b