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Lab 6 of PHYS 2C LAB
Lenses and Mirrors
We use four optical components only: +75mm convex lens, +155mm convex lens, the concave mirror, and variable aperture
All given numbers of measured data are for your reference only. You have to correct them into the right value with significant figures if you think any of those numbers is incorrect!
Section 4:
75 mm convex lens and Variable aperture
All you have to do here is to observe the phenomena of Section 4(b).
Skip the work of Section 4(a) and (c).
No graph is required.
DATA Table of Section 4:
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75 convex lens and variable aperture, |
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Aperture size, A, Unit: mm |
The closest position still giving a focused image, X1, (to the lens), Unit: ( ) |
The farthest position still giving a focused image, X2, (to the lens), Unit: ( ) |
Depth of field, D=|X1-X2|, UNIT: ( ) |
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30 |
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10 |
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3 |
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Question 4-1 on page 38
How does depth of field depend on aperture size?
Requirement:
(0.5 POINT) Does depth of field increase or decrease when you increase the aperture size, A?
Error estimation (1 POINT)
When the aperture size is roughly 30mm, the depth of field is D mm. Therefore, in Section 1, 2, and 3, every reading concerning with s or s’ will have an error, roughly ± (D/2) mm, because that the size of your every lens is also 30mm, approximately. In fact, it will depend on the data you collect in Section 4.
For example, s’ = 100 mm ± (D/2) mm or s’ = 115 mm ± (D/2) mm
Therefore, be careful about the significant figures of your every reading concerning with S or S’.
YOUR READING of S’ CAN NOT BE VERY ACCURATE!
Review PAGE 2 and 3 in your laboratory manual if you still do not understand the trap I set up here.
1, The significant figures of your Image Distance, S', will cost you 0.5 points.
2, The significant figures of your Expected Magnification, the theoretical m, will cost you 0.5 points.
This concerns your Image Distance, S' and Object Distance, S.
3, The significant figures of your Lateral Magnification, the experimental m, will cost you 0.5 points.
This concerns your Image Size, L' and Object Size, L.
Use a ruler to measure your L and L’.
L and L’ are coming from your direct measurements. Be careful! Here is another trap!
Section 1:
75 mm convex lens
You have to give me the graph "s' versus s."
DATA Table of Section 1:
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75 mm convex lens |
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Object Distance, S, Unit: mm |
Image Distance, S', Unit: ( ) |
Lateral Magnification, m(Experimental) = - L'/L |
Expected Magnification, m(Theoretical) = - s'/s |
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100 |
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150 |
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200 |
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250 |
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300 |
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Question 1-1 on page 36
Does this make a good straight line?
Requirement:
| Graph "s' versus s" |
Regression Coefficient |
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Theoretical |
( + / - ) 1 |
|
Measured |
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%error |
% |
Never just write something like: " It does not make a straight line." Or you will lose 1 point.
You have to give me the graph "1/s' versus 1/s" with the regression line.
Define Image Length as L' and Object Length as L.
Then, Lateral Magnification, m (Experimental) = - L’/L
L and L’ are coming from your direct measurements.
Question 1-2 on page 36
Does this plot match expectations?
What is the measured value of "f"?
Requirement:
| Graph "1/s' versus 1/s" |
(y - Intercept) - 1, unit: ( ) |
Slope, unit: N.A. |
Regression Coefficient |
|
Theoretical |
feffective = |
- 1 ? | - 1 |
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Measured |
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%error |
% | % | % |
Never just write something like: "This graph fits very well." Or you will lose 1 point.
Section 2:
+75 mm convex lens and +150mm convex lens
DATA Table of Section 2:
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75 mm convex lens and +150mm convex lens |
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Object Distance, S, Unit: mm |
Image Distance, S', Unit: ( ) |
Lateral Magnification, m(Experimental) = - L’/L |
Expected Magnification, m(Theoretical) = - s'/s |
%error of m |
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75 |
% | |||
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100 |
% | |||
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120 |
% | |||
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150 |
% | |||
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200 |
% |
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You have to give me the graph "1/s' versus 1/s" with the regression line.
Define Image Length as L' and Object Length as L.
Then, Lateral Magnification, m (Experimental) = -L’/L
L and L’ are coming from your direct measurements.
And you should calculate the effective focal length f.
This is your theoretical f.
Effective focal length, f, = (f1f2)/(f1+f2)
Question 2
Does this make a good straight line? What is the measured value of "f"?
Requirement:
| Graph "1/s' versus 1/s" |
(y-Intercept) - 1, unit: ( ) |
Slope, unit: N.A. |
Regression Coefficient |
|
Theoretical |
feffective = |
- 1 ? | - 1 |
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Measured |
|||
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%error |
% | % | % |
Section 3:
The concave mirror
All you have to do here is to observe the phenomena.
DATA Table of Section 3:
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The concave mirror Refer to Fig.7.3 on page 34 |
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Object Distance, S, Unit: mm |
Image Distance, S', Unit: ( ) |
Lateral Magnification, m(Experimental) = - L’/L |
Expected Magnification, m(Theoretical) = - s'/s |
%error of m |
|
125 |
% | |||
|
200 |
% | |||
|
400 |
% | |||
No graph or no question is required.
Define Image Length as L' and Object Length as L.
Then, Lateral Magnification, m (Experimental) = -L’/L
L and L’ are coming from your direct measurements.
How to predict the theoretical slope, [M], and y-intercept, [B] on your graphs?
Refer to Supplement to Graphical Analysis.
Additional Question, Please write down a simple conclusion of the whole Lab
6 of Phys 2C Lab.
Requirement:
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