Thin Lenses

Statement of Purpose
To observe the effects on light through a thin lense.

Procedure
Measure the focal length of the lense with two parallel rays.

The distance at which the two parallel rays converge is the focal length of the lense.

f = 5 +- 1cm

We focus light at a particular distance for several distances and measure the height of the object for which we used the tip of the arrow.

Data
d0 (± .1 cm) di (± .1 cm) h0 (± .1 cm) hi (± .1cm) M
5f = 25.000 7.000 1.800 0.400 0.23 ± 0.07
4f = 20.000 7.300 1.800 0.600 0.34 ± 0.07
3f = 15.000 8.200 1.800 0.700 0.39 ± 0.08
2f = 10.000 10.500 1.800 1.800 1.0 ± 0.1
1.5f =7.500 18.700 1.800 4.100 2.3 ± 0.2

 Object distance vs Image distance

Inverse Image Distance vs Negative Inverse Object Distance

Slope = .9475
y-intercept = .184

We see that at distances behind the focal length the virtual image reflects off of the back wall of the lense.

Conclusion
The y-intercept of the graph represents the 1/f in the lense maker's equation and since the slope is close to one we can write the equation of the graph.

y = x + (1/.184)

This equation relates the object distance vs the image distance.