1. MEASUREMENT OF THE FOCAL LENGTH OF A CONCAVE MIRROR
Find a rough value for f.
Measure object distance u and image distance v.
Find f from
Plot 1/u against 1/v. Where the graph cuts the axes gives a value for 1/f.
Precautions
Avoid parallax measuring distances
Make u greater than the rough valve for f.

2. VERIFICATION OF SNELL’S LAW OF REFRACTION
Graph Sin i (y axis) and Sin r (x axis)
Refractive index is the slope
Precautions
Don’t have angle i too small to reduce percentage error
Use a sharp pencil to draw the lines
Ray box
Glass block i r

3. MEASUREMENT OF THE REFRACTIVE INDEX OF A LIQUID
Measure the real depth of the container and the distance from the back of the mirror to the pin in the cork.
n = real depth / apparent depth
Precautions
Repeat with various containers of differing heights and get an average.
Make sure the water goes to the back of the mirror.

4. MEASUREMENT OF THE FOCAL LENGTH OF A CONVERGING LENS
Find a rough value for f.
Measure object distance u and image distance v.
Find f from
Plot 1/u against 1/v. Where the graph cuts the axes gives a value for 1/f.
Precautions
Avoid parallax measuring distances
Make u greater the than the rough valve for f.