This does not happen on my averaged results, which means that my graph is not accurate. This means that my Graph does not support my prediction.
A better way of getting results that are more proportional would be to use ‘Snell’s Law’. This means that you multiply the angle of incidence by sin and the angle of refraction also by sin; separately.
These results will now be plotted on another graph
Analysis and considering
This graph is a straight line suggesting that it is in proportion. This means that my prediction is correct. The angle of incidence is proportional to the angle of refraction.
The gradient from this graph is G=I/r G=
Gradient is=
This point shows that my graph is accurate as in the book it suggests that the refracted index should be 1.5.
The evidence below is from the refracted index, proving that my prediction is correct and that my results are accurate.
By looking at my graph, you can see that my prediction is correct.
Angle of incidence x sine=0.5, angle of refraction x sine=0.35
Doubled: Angle of incidence x sine=0.87, angle of refraction x sine=0.62
Now if you round the numbers up-
Angle I x sine=0.5, angle r x sine= 0.6
Doubled Angle I x sine=1, angle r x sine= 1.2
Evaluation
By looking at the evidence I have gathered for this investigation, I can see that my results I gathered are accurate. This can be shown especially on the ‘smells’ graph as the line of best-fit shows that there are no anomalous points.
I repeated the experiment to gather a good range of results. I f I wanted to show an even more accurate set of results I could have used a greater range of results.
Though this investigation shows that I have done the experiment correctly and gained the correct information, I was still faced with some slight problems, which may have affected the results that I gathered.
∙The ray of light refracted from the block was thick and long. I was only able to place a few points to outline where the line travelled. This may have made my lines slightly out of line and inaccurate. Spending more time on drawing the line out for more accuracy could prevent this.
∙The glass block was not always placed exactly in the correct position, and moved slightly when I plotted the ray line. I could have cello taped the block of glass down whilst drawing on the lines.
∙When plotting the angle of the line it was slightly inaccurate once the line had been drawn, as the pencil line was thicker than a protractor line, meaning that the figures I read could have been a degree or two off the correct point. To prevent this I could have used a slightly larger protractor.
The quality of the snells graph was much better than my first graph, as it is more accurate because the gradient is close to the refractive index. The snells graph is also more accurate as the line of best-fit shows that there are no anomalous points.
I could have improved the investigation by repeating the experiment a few more times to gather more results, to compare the accuracy.
The main problem with this investigation was that it was hard to plot the ray line and to plot the angles accurately. To prevent this the block could have been larger because this would mean that the ray line would be easier to draw on as it wouldn’t be quite as thick and the angles would have been easier to draw on if there was a larger and clearer protractor as points were slightly out of place.
