Part 1: Single Lens System

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Objective:

Part 1: Single Lens System

Step 1: Lens as Magnifying Glass

(Do all the lenses magnify? Which is the stronger magnifier, i.e. which magnifies more when used as a magnifying glass? Which is the “weaker magnifier?)

Step 2: Hallway Method of Determining Focal Lengths

Raw DataCalculated Data

Lens / Image Distance
s’
( ) / Focal Length
f
( )
+5
+10
-15 / no image formed

Note: The Thin Lens Equation states 1/f = 1/s + 1/s’. Since ss’, fs’.

Step 3: Image Formation

Raw DataCalculated Data

Object Height
h
( ) / Object Distance
s
( ) / Image Distance
s’
( ) / Image Height
h’
( ) / Focal Length
f
( ) / Lateral Mag.
M = h’/h / Lateral Mag.
M = -s’/s

Average f=

Sample Calculations:

Focal Length 1/f = 1/s + 1/s’ =

f =

Lateral Mag.M = h’ / h =

Lateral Mag.M = -s’ / s =

{Step 4: omitted}

Step 5: Method of Conjugate Foci

Raw DataCalculated Data

Object-Image Distance
D
( ) / Lens
Position 1
x1
( ) / Lens
Position 2
x2
( ) / Difference in Lens Positions
d
( ) / Focal Length
f
( )

Calculations:

d = x2 – x1 =

f = (D2d2) / 4D =

Results:

(Compare the values of the focal length you determined by the various methods in Steps 2,3 and 5 for the +10 lens. Comment on whether they agree with one another within experimental uncertainty.)

(Comment on the values you found for magnification using h’/h and –s’/s in Step 3. Do the two values agree with each other for each run?)

(Is there just one value for magnification for this+10 lens? If not, what does the magnification depend upon?)

Uncertainties:

(What were the sources of measurement uncertainty? Which source was the largest contributor to measurement uncertainty? Does the measurement uncertainty alone account for any differences that you found between values of identical quantities?)

Part 2: Two-Lens System

Step 1: Two Positive Lenses

Raw Data Calculated Data

Initial Screen Position
xi
( ) / Lens 2 Position
x2
( ) / Final Screen Position
xf
( ) / Lens 2 Object Distance
s2
( ) / Lens 2 Image Distance
s’2
( ) / Lens 2 Focal Length
f2
( )

Calculations:

s2 = x2 – xi =

s’2 = xf – x2 =

1/f2 = 1/s2 + 1/s’2 =

f2 =

Step 2: One Positive and One Negative Lens

Raw Data Calculated Data

Initial Screen Position
xi
( ) / Negative
Lens Position
x2
( ) / Final Screen Position
xf
( ) / Neg. Lens Object Distance
s2
( ) / Neg. Lens Image Distance
s’2
( ) / Neg. Lens Focal Length
f2
( )

Calculations:

s2 = x2 – xi =

s’2 = xf – x2 =

1/f2 = 1/s2 + 1/s’2 =

f2 =

Results:

(Is the focal length for Lens 2 in Step 1 close to the value that you determined in the hallway?)

(Is the focal length of the negative lens indeed negative? How does it compare to the nominal value of -15 cm?)

Uncertainties: