A Level Physics Practice Exam

In Young's double slit experiment, how is the visibility of a diffraction pattern determined?

1. By measuring the light intensity

2. By analyzing the angle of first order maxima

3. By counting the number of slits

4. By varying the wavelength of light

The correct answer is: By analyzing the angle of first order maxima

In Young's double slit experiment, the visibility of the diffraction pattern is fundamentally linked to the interference of light waves as they pass through the slits. The visibility is quantifiably determined by the intensity of the light at various points of the pattern, particularly at the maxima and minima. The angle of the first order maxima plays a significant role in understanding the diffraction pattern because it directly relates to the path difference between the light waves originating from the two slits. By analyzing this angle, we can infer how the conditions for constructive and destructive interference are met, impacting the visibility of the pattern as a whole. However, while the angle of the first order maxima offers insights into the diffraction and interference process, visibility itself is typically assessed by comparing the intensity of the bright and dark regions of the pattern. This comparison reveals the contrast of the pattern, thus making it an important factor in determining visibility, which might make another choice more suitable. The intensity of light helps quantify how clearly one can see the bright and dark fringes, affecting the visibility. Counting the number of slits provides information about the complexity of the interference pattern, as more slits lead to sharper and more defined fringes, but it doesn't directly measure visibility. Similarly, varying the wavelength of