In each case sin i/sin r is (approximately) constant; therefore this verifies Law. Snell’s Diagram to show: A target medium e.g. glass block Incident ray (from ray box) Perpendicular / normal and refracted ray Label angles and i r Correct sin and sin values for six points i r sin 0.500 0.643 0.766 0.819 0.866 0.906 0.939 Label axes correctly on graph paper i Plot six points correctly sin 0.325 0.438 0.500 0.544 0.588 0.615 0.643 r Straight line showing good distribution A straight line through the origin shows that sin is proportional to sin i r Correct slope method (n = ) 1.41 [range: 1.38 1.52] – To reduce the (percentage) error Elaboration e.g. difficult to measure /read angles, < , etc. r i See diagram, plus ray-box. Mark the position of the incident and exit rays and also the outline of the block. Remove the block then measure the angle between the refracted ray and the normal using a protractor. sin i 0.34 0.50 0.64 0.77 0.87 0.94 sin r 0.24 0.33 0.44 0.50 0.59 0.64 Refractive index = slope = y2 y1 / x2 x1 n = 1.49  – – There would be a greater percentage error associated with measuring smaller angles. Common Test errors State the laws of refraction of light use the word in your answer Don’t “reflection” What is meant by the refractive index of a material? Include the phrase light travels from a vacuum into that “as medium” Explain how a signal is transmitted along an optical fibre. Give three separate points Experiment to verify law Snell’s Using the recorded data, draw a suitable graph It must be a graph of against {not i and r} sin i sin r Using your graph, find the refractive index You must calculate the slope of the graph by using two points which are clearly marked on the graph {so you can’t take points from the table unless they also happen to be on the line of best fit which you have drawn}
In each case sin i/sin r is (approximately) constant; therefore this verifies Snell’s Law. Diagram to show: A target medium e.g. glass block Incident ray (from ray box) Perpendicular / normal and refracted ray Label angles i and r Correct sin i and sin r values for six points sin i 0.500 0.643 0.766 0.819 0.866 0.906 0.939 sin r 0.325 0.438 0.500 0.544 0.588 0.615 0.643 Label axes correctly on graph paper Plot six points correctly Straight line showing good distribution A straight line through the origin shows that sin i is proportional to sin r Correct slope method (n = ) 1.41 [range: 1.38 – 1.52] To reduce the (percentage) error Elaboration e.g. difficult to measure /read angles, r < i , etc. See diagram, plus ray-box. Mark the position of the incident and exit rays and also the outline of the block. Remove the block then measure the angle between the refracted ray and the normal using a protractor. sin i 0.34 0.50 0.64 0.77 0.87 0.94 sin r 0.24 0.33 0.44 0.50 0.59 0.64 Refractive index = slope = y2 – y1 / x2 – x1  n = 1.49 There would be a greater percentage error associated with measuring smaller angles. Common Test errors State the laws of refraction of light Don’t use the word “reflection” in your answer What is meant by the refractive index of a material? Include the phrase “as light travels from a vacuum into that medium” Explain how a signal is transmitted along an optical fibre. Give three separate points Experiment to verify Snell’s law Using the recorded data, draw a suitable graph It must be a graph of sin i against sin r {not i and r} Using your graph, find the refractive index You must calculate the slope of the graph by using two points which are clearly marked on the graph {so you can’t take points from the table unless they also happen to be on the line of best fit which you have drawn}
4.%20Refraction.docx