In an experiment to verify Snell's law, a student measured the angle of incidence i and the angle of refraction r for a ray of light as it passes from air into glass - Leaving Cert Physics - Question 3 - 2022

The student followed these steps to determine the angle of refraction:

1. Incident Ray: The angle of incidence (i) was measured from the normal (perpendicular line) at the point of incidence on the block.
2. Reflected Ray: The refracted ray was traced as it emerged into the glass, making sure to draw it straight out.
3. Emergent Ray Measurement: Using a protractor, the angle of refraction (r) was measured from the normal where the ray exits the glass.

To verify Snell's law, the student should create a graph with:

1. X-axis: Angle of incidence (i) in degrees.
2. Y-axis: Sine of angle of refraction (sin(r)).
3. Data Point Plotting: Values of sin(i) and sin(r) should be calculated and plotted.

The formula used:

• Sine formula: $sin(r) = \frac{r}{n}$ Where n is the refractive index.

By determining the slope of the line plotted on the graph (where the line fits the points), the refractive index (n) can be calculated:

1. From the slope: $n = \frac{sin(i)}{sin(r)}$ Thus, calculating using the data values provided for sin(i) and sin(r). Assume the slope to be approximately 1.4 based on the data points.

If the angle of incidence is zero degrees, the ray of light would be perpendicular to the boundary of the glass.

• Observation: There would be no bending of the light ray, meaning that the light would travel straight without refraction. Therefore, the path of the ray would continue in its original direction into the glass.