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Under certain conditions, light can undergo diffraction and interference - Leaving Cert Physics - Question 7 - 2012
Question 7
Under certain conditions, light can undergo diffraction and interference. (i) Explain the underlined terms. (ii) Describe an experiment to demonstrate the wave nat... show full transcript
Worked Solution & Example Answer:Under certain conditions, light can undergo diffraction and interference - Leaving Cert Physics - Question 7 - 2012
Step 1
Explain the underlined terms.
Answer
Diffraction is the spreading out of waves when they encounter an obstacle or pass through an aperture. It can be observed at the edges of an opening, where the waves bend and create patterns.
Interference occurs when two waves meet and combine, leading to constructive (amplitude increases) or destructive (amplitude decreases) interference patterns.
Step 2
Describe an experiment to demonstrate the wave nature of light.
Answer
Apparatus
- Light source (narrow beam)
- Diffraction grating
- Screen
Procedure
- Shine a narrow beam of light through the diffraction grating onto a screen.
- Observe the pattern of light and dark bands created on the screen.
Observation/Conclusion
The interference pattern confirms the wave nature of light, indicating that it spreads and interacts similarly to waves in water.
Step 3
Step 4
Describe an experiment to demonstrate the polarisation of light.
Answer
Apparatus
- Two pieces of Polaroid sunglasses
Procedure
- Begin with one piece of Polaroid and observe the light passing through it.
- Then, place the second piece of Polaroid in front of the first, gradually rotating it.
Observation/Conclusion
When the two pieces are aligned, light passes through. As the second piece is rotated, the intensity of the light diminishes until it is blocked, demonstrating polarisation.
Step 5
Step 6
Why are Polaroid sunglasses more effective than non-Polaroid sunglasses at reducing glare?
Answer
Polaroid sunglasses are more effective because they filter out reflected light that is polarised in a single plane. Non-Polaroid sunglasses do not selectively reduce glare, allowing more reflected light to pass through.