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Diffraction and interference are properties associated with waves - Leaving Cert Physics - Question 8 - 2018
Question 8
Diffraction and interference are properties associated with waves. (i) Explain the underlined terms. (ii) Describe an experiment to demonstrate the wave nature of ... show full transcript
Worked Solution & Example Answer:Diffraction and interference are properties associated with waves - Leaving Cert Physics - Question 8 - 2018
Step 1
Explain the underlined terms.
Answer
Diffraction is the bending and spreading out of waves around barriers or the edges of an opening. It occurs when a wave encounters an obstacle and can be observed when waves pass through a narrow slit or around corners.
Interference is the phenomenon that occurs when two or more waves meet and superimpose, leading to a new wave pattern. This can result in areas of constructive interference, where waves add together, and destructive interference, where they cancel each other out.
Step 2
Describe an experiment to demonstrate the wave nature of light.
Answer
To demonstrate the wave nature of light, we can use a double-slit experiment:
Apparatus:
- A coherent light source (like a laser)
- A double-slit apparatus (grating or Young’s slits)
- A screen to observe the pattern
Procedure:
- Shine the laser light through the double-slit apparatus.
- Observe the pattern formed on the screen, noting alternating bright and dark fringes.
- This pattern is indicative of the wave nature of light as it demonstrates interference.
Observation/Conclusion: The observed pattern on the screen confirms that light behaves as a wave, displaying both diffraction and interference effects.
Step 3
Step 4
Describe an experiment to demonstrate the polarisation of light.
Answer
To demonstrate the polarisation of light:
Apparatus:
- Two pieces of polarised sheet
- A light source (like a lamp)
Procedure:
- Position the first polarised sheet in front of the light source.
- Observe the light that passes through.
- Place the second polarised sheet in front of the first and slowly rotate it.
- Note how the intensity of the light changes as you rotate the second sheet, becoming dimmer at certain angles and brighter at others.
Observation/Conclusion: When the sheets are aligned, maximum light passes through; at right angles, the light is blocked, demonstrating the property of polarisation.
Step 5
Step 6
Describe how these colours can be used to create any image.
Answer
These three primary colours (red, green, and blue) can be combined in various proportions to create a wide spectrum of colours. By adjusting the intensity of each colour, any image can be produced. For example:
- Red and green combine to create yellow.
- Red and blue combine to make magenta.
- A full combination of red, green, and blue at different intensities can produce all visible colours.