Photo AI
In an experiment a beam of monochromatic light passes through a diffraction grating and strikes a screen - Leaving Cert Physics - Question 7 - 2009
Question 7
In an experiment a beam of monochromatic light passes through a diffraction grating and strikes a screen. (i) Explain the underlined terms. (ii) Describe what is o... show full transcript
Worked Solution & Example Answer:In an experiment a beam of monochromatic light passes through a diffraction grating and strikes a screen - Leaving Cert Physics - Question 7 - 2009
Step 1
Explain the underlined terms.
Answer
-
Monochromatic Light: This refers to light of a single color or wavelength. It means that the light consists of one specific frequency, which gives it a distinct color, as opposed to light that contains multiple wavelengths.
-
Diffraction Grating: A diffraction grating is an optical component with a regular pattern that disperses light into its component colors or wavelengths. It works by having many closely spaced slits or grooves that cause the light to bend and spread out, creating visible patterns based on constructive and destructive interference.
Step 2
Describe what is observed on the screen.
Answer
On the screen, distinct bright and dark bands can be observed. The bright bands, known as interference maxima, occur where constructive interference happens, while the dark bands, known as interference minima, result from destructive interference of the light waves. This pattern illustrates the wave nature of light.
Step 3
Explain, with the aid of a diagram, how this phenomenon occurs.
Answer
When monochromatic light passes through the diffraction grating, it is divided into several beams diverging at specific angles. The overlapping waves from adjacent slits combine in such a way that some waves reinforce each other (constructive interference), resulting in bright spots on the screen, while others cancel each other (destructive interference), creating dark spots. Here's a visual representation:
|
|
Grating -----> Light Waves
|
↓
Bright Dark Bright ...
Spot Spot Spot
This diagram shows the principle of diffraction where the angles of divergence depend on the slit spacing and the wavelength of light.
Step 4
What does this experiment tell us about the nature of light?
Answer
This experiment provides insights into the wave nature of light, as evidenced by the interference pattern. It suggests that light exhibits properties similar to waves, such as diffraction and interference, further confirming the wave theory of light.
Step 5
Step 6
What measurements must be taken to determine the property you named?
Answer
To determine the wavelength of light, the following measurements should be taken:
- The distance between the adjacent bright spots on the screen.
- The distance from the grating to the screen.
- The distance between the slits in the diffraction grating. These measurements allow calculating the wavelength using the formula:
ext{Wavelength} = rac{ ext{Distance between adjacent spots} imes ext{Distance to screen}}{n imes ext{Distance between slits}} where n is the order of the interference.