Download Practice lab Final - La Salle University

SHOW WORK! Supply units wherever applicable. Label graphs. Do not waste too much
time on any one part of the exam.
Lenses
1. The light source in the set-up shown below was placed at some distance to the lens and
then the screen’s position was varied until an image was formed on it.
Light source
lens
screen
The data collected is contained in the following table.
Distance from Distance from The focal
light source to lens to screen length of the
lens (cm)
(cm)
lens (cm)
25
58
30
42
35
35
40
31
45
28
50
27
55
26
60
25
65
24
Average ( )
Stand. Dev.
( )
Magnification
Calculate the focal length and magnification for each trial. Calculate the average focal length
as well as the standard deviation.
Copy and paste the data into Excel and make a plot of the reciprocal of the lens-screen
distance versus the reciprocal of the source-lens distance. Fit it to a straight line. Paste it
into this document.
PLOT GOES HERE.
Fill in the table below regarding the plot.
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Theory
Slope ( )
X intercept (
Y intercept (
Your graph
)
)
Two-Slit Interference
2. A blue laser with a wavelength of 472 nm was shone through a two-slit apparatus, which
was 2.45 m from the screen/wall. The distance from the center of one fringe to the center
of the fourth consecutive fringe (as shown below) was found to be 1.20 cm.
Determine the distance between the slits.
Distance between slits ( )
What would happen to the distance between the fringes if a red laser was used? Explain.
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RC Circuits
3. The data in the Discharge worksheet of the file p106_Practice_lab_final.xls is for a
circuit with a capacitor and a resistor. Fit the data to the form appropriate for a
discharging capacitor. Find the electric potential and time constant parameters. Paste the
plot in this document. If the resistor has a resistance of 3.45 k, then find the value of the
capacitance.
PLOT GOES HERE.
Electric Potential parameter (
):
Time constant ( ):
Capacitance (
):
4. The data in the Charge worksheet of the file p106_lab_final.xls is for a circuit with a
battery (DC power supply), a capacitor and a resistor. Fit the data to the form appropriate
for a charging capacitor. Find the electric potential and time constant parameters. Paste
the plot in this document. If the resistor has a resistance of 2.15 k, then find the value of
the capacitance.
PLOT GOES HERE.
Electric Potential parameter (
):
Time constant ( ):
Capacitance (
):
5. Capacitor C1 was connected to a 5.00-V battery for long enough time to charge it. It was
then disconnected from the battery. A second capacitor C2 was then placed in parallel
with C1 and both were found to have voltages of 3.25 V. Determine the ratio of
capacitances C2/C1. Show work.
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How was the voltage measured?
6. An experiment with capacitors was set up as shown in the figure below. Also below is a
set of circuit diagrams. To which diagram does the experimental setup correspond (A, B,
C, D, or E. None of these? Explain.
Corresponding diagram:
A.
B.
V1
V1
C1
C2
C3
C1
C2
C3
C.
D.
C2
V1
C2
V1
C1
C3
C3
C1
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7. Use the surface plot and contour plot of a charge distribution provided below to draw the
electric field lines. Also indicate places on the plot where the electric potential is zero
and where the electric field is zero.
9-10
8-9
10
9
8
7
6
5
4
3
2
1
0
-1
-2
-3
-4
-5
-6
-7
-8
-9
-10
7-8
6-7
5-6
4-5
3-4
2-3
1-2
0-1
-1-0
-0.08
-3--2
-4--3
0.1
0.1
0.075
0.05
-5--4
0.025
1.56125E-17
-0.025
0.04
-0.05
-0.075
-0.1
-0.02
-2--1
-6--5
-7--6
-8--7
-9--8
-10--9
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9-10
-0.095
-0.08
7-8
-0.065
6-7
-0.05
5-6
-0.035
4-5
-0.02
3-4
-0.005
2-3
0.01
1-2
0.025
0.04
0.055
0.1
0.08
0.06
0.04
0.02
1.56125E-17
-0.02
-0.04
-0.06
-0.08
0.07
-0.1
8-9
0-1
-1-0
-2--1
-3--2
-4--3
0.085
-5--4
0.1
-6--5
-7--6
-8--7
-9--8
-10--9
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