# Physics Software

## Focal length of thin lens

The relationship of focal length, object to lens and lens to image distance shown below. $$\frac{1}{f} = \frac{1}{a} + \frac{1}{b}$$ Here $f$ is focal length, $a$ is lens to object distance, $b$ is lens to image distance. From the equation above the focal length is $$f = \frac{ab}{a + b}$$ Measure up to 5 set of $a$, $b$ and fill the table below.

## Focal length of convex lens

 # Distance to object $$a(m)$$ Distance to image $$b(m)$$ 1 2 3 4 5

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## Focal length of concave lens

 # First location of the screen $D_1 (m)$ Second location of the screen $D_2 (m)$ Location of the concave lens $O_2 (m)$ 1 2 3 4 5

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