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.

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

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.

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.