In an optics experiment, a candle is placed various distances (x, in cm) from a lens. An inverted image of the candle flame is found on the other side of the lens at a distance (y, in cm) from the lens. The uncertainty in y varies quite a bit: large when y is large and small when y is small; the estimate for δy is given in the data table.

The lens equation predicts:

1/x + 1/y = 1/f

where f is a constant called the focal length of the lens.

The lens equation can be put in standard form:

1/y = A + B/x

where: B=-1 and A=1/f

  1. Fit this data to an inverse x & y relationship
  2. Consider the prediction of the lens equation. Does this evidence (data) confirm or contradict this scientific claim? Support your answer quantitatively.
  3. Properly report (sigfigs, error, units) the B parameter of the best-fit function.
  4. Fit this data to an inverse x & y relationship with B held fixed at -1
  5. Properly report (sigfigs, error, units) the A parameter of this best-fit function.
  6. Use a spreadsheet to calculate the focal length of the lens from A, and properly report (sigfigs, error, units) the value.
  7. Self-document the spreadsheet and turn in a hardcopy of the page.
  8. Make a hardcopy plot of the data with best-fit curve. Make an additional hardcopy plot with scales chosen so as to linearize the curve.

X
(cm)
Y
(cm)
δY
(cm)
18 88 15
20 60 6
22 50 3
26 35.5 1.5
30 30.5 1
40 24.5 0.5
50 21.0 0.3
60 20.1 0.2
75 19.0 0.15
90 17.9 0.1