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A student carried out an experiment to verify Snell’s law of refraction by measuring the angle of incidence $i$ and the angle of refraction $r$ for a ray of light entering a glass block - Leaving Cert Physics - Question 2 - 2006
Question 2
A student carried out an experiment to verify Snell’s law of refraction by measuring the angle of incidence $i$ and the angle of refraction $r$ for a ray of light en... show full transcript
Worked Solution & Example Answer:A student carried out an experiment to verify Snell’s law of refraction by measuring the angle of incidence $i$ and the angle of refraction $r$ for a ray of light entering a glass block - Leaving Cert Physics - Question 2 - 2006
Step 1
Draw a labelled diagram of the apparatus used in the experiment.
Answer
To draw the apparatus used in the experiment, include the following components:
- Glass Block: Draw a rectangular block to represent the glass.
- Ray Diagram: Indicate the incident ray approaching the glass block at an angle, labeled as angle of incidence .
- Reflected Ray: Show a line representing the refracted ray exiting the glass block, at an angle .
- Protractor: Illustrate the protractor measuring the angles, ensuring to label the angles clearly.
- Light Source: Represent the light source that emits the ray of light entering the glass block, and denote its position.
- Emerging Ray: Mark the point of exit where the refracted ray emerges from the glass block.
Make sure all parts are labeled clearly and neatly to adhere to the marking scheme.
Step 2
Describe how the student found the position of the refracted ray.
Answer
The student found the position of the refracted ray using the following steps:
- Aligning the Apparatus: The student aligned the glass block on a flat surface with the light source positioned at the correct angle.
- Drawing the Incident Ray: The path of the incident ray was drawn towards the glass block, ensuring the angle of incidence was accurately measured.
- Observing the Emerged Ray: After the light entered the glass block, the student adjusted their view to see where the ray exited the block, labeling this as the refracted ray.
- Using a Ruler: A ruler was used to help draw the refracted ray accurately from the exit through the glass block to the observer’s position.
- Marking the Point of Exit: The point where the refracted ray exited was marked clearly to help with further measurements.
Step 3
How did the student measure the angle of refraction?
Answer
The student measured the angle of refraction using the following method:
- Using a Protractor: The protractor was aligned along the point where the refracted ray exited the glass block.
- Measuring the Angle: The angle formed between the normal line (perpendicular to the surface at the point of exit) and the refracted ray was measured to determine the angle of refraction .
- Repeat Measurements: This process was repeated for each angle of incidence to ensure accuracy in the measurements collected.
Step 4
Step 5
Use the data to verify Snell’s law of refraction.
Answer
To verify Snell’s law of refraction, we will use the collected data and the relationship defined by Snell’s law, which states:
From the data collected:
- For each angle of incidence and the corresponding angle of refraction , calculate rac{\sin i}{\sin r} for each pair.
Since Snell's law implies that rac{\sin i}{\sin r} should be constant for all measured angles, the values obtained from the table can be compared:
- The calculated ratios from data [1.53, 1.50, 1.50] are close to each other, indicating that Snell's law holds true in this experiment. This consistency suggests that the refractive index is approximately constant for the material of the glass block used.