Physics 132-04 Test 2
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Questions (5 for 8 pts. apiece) Answer in complete, well-written
sentences WITHIN the spaces provided.
- Draw what you think the field lines and equipotential lines between parallel plates
will look like. Explain you reasoning.
- In our simulations of the electric potentials for a point charge and for an electric dipole
we found they behaved differently as a function of the distance
from origin.
Did the electric dipole potential fall faster, slower, or the same as the point charge?
Explain the result you observed.
- For a circuit you analyzed like the one shown below
how is the voltage drop across
related
to the potential drop across
?
Explain your observation.
DO NOT WRITE BELOW THIS LINE.
- Consider a situation where there is a uniform magnetic field in space that
points in the
direction
and the velocity of a particle
with charge
in the field is in the
direction
.
What is
the angle between the magnetic field vector and the velocity vector?
What is
is terms of the magnitudes of
,
, and
and the appropriate unit
vectors?
- Why is it possible for a bird to sit on a high-voltage wire without getting
electrocuted?
Problems (3). Clearly show all reasoning for full credit.
Use a separate sheet to show your work.
1. |
18 pts. |
Four identical charges
are located on the corners of a rectangle as shown in the figure.
What is the total, vector electric force exerted on
the charge at the lower, right corner
in terms of , , , the appropriate unit vectors, and any other necessary constants?
|
DO NOT WRITE BELOW THIS LINE.
2. |
18 pts. |
A rod of length (see figure) lies along the axis with its left
end at the origin.
It has a nonuniform charge density
, where is a positive
constant.
What is the electric potential at in terms of , , , and any other necessary
constants?
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3. |
24 pts. |
A proton ( , , ), a deuteron ( , , ),
and a nucleus ( , )
with the same kinetic energies enter a region of uniform magnetic field moving
perpendicular to .
What is the ratio of their radii in the magnetic field?
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Physics 132-4 Constants
![$k_B$](img29.png) |
![$1.38\times 10^{-23}~J/K$](img30.png) |
proton/neutron mass |
![$1.67\times 10^{-27}~kg$](img31.png) |
![$1 ~ u$](img32.png) |
![$1.67\times 10^{-27}~kg$](img31.png) |
![$g$](img33.png) |
![$9.8~m/s^2$](img34.png) |
Gravitation constant |
![$6.67 \times 10^{-11}~N-m^2/kg^2$](img35.png) |
Earth's radius |
![$6.37\times 10^6~m$](img36.png) |
Coulomb constant ( ) |
![$8.99\times 10^{9} {N-m^2 \over C^2}$](img38.png) |
Electron mass |
![$9.11\times 10^{-31}~kg$](img39.png) |
Elementary charge ( ) |
![$1.60\times 10^{-19}~C$](img41.png) |
Proton/Neutron mass |
![$1.67\times 10^{-27}~kg$](img31.png) |
Permittivity constant ( ) |
![$8.85\times 10^{-12} {kg^2\over N-m^2}$](img43.png) |
![$\rm 1.0~eV$](img44.png) |
![$1.6\times 10^{-19}~J$](img45.png) |
![$\rm 1 ~MeV$](img46.png) |
![$10^6 ~ eV$](img47.png) |
atomic mass unit ( ) |
![$1.66\times 10^{-27}~kg$](img49.png) |
Physics 132-4 Equations
=100000
=2.5in
The algebraic sum of the potential changes across
all the elements of a closed loop is zero.
The sum of the currents entering a junction
is equal to the sum of the currents leaving the
junction.
The Periodic Chart.