The purpose of finding the 2nd dark fringe angle for diffraction on a single slit is to determine the angle at which the maximum diffraction pattern occurs. This angle can help in understanding the properties of light and the behavior of waves passing through a narrow opening.
The 2nd dark fringe angle can be calculated using the formula: θ = λ/d, where θ is the angle, λ is the wavelength of light, and d is the width of the slit. It can also be determined experimentally by measuring the distance between the central bright spot and the 2nd dark fringe on a diffraction pattern.
The large distance of 1.5x10^6m is important for this calculation because it allows for a more accurate measurement of the angle. As the distance increases, the angle between the central bright spot and the 2nd dark fringe becomes smaller, making it easier to measure precisely.
The width of the slit directly affects the 2nd dark fringe angle. A wider slit will result in a smaller angle, while a narrower slit will produce a larger angle. This is because a wider slit allows for more light to pass through, creating a wider diffraction pattern and a smaller angle between the central bright spot and the 2nd dark fringe.
Other factors that can affect the calculation of the 2nd dark fringe angle include the wavelength of light, the distance between the slit and the screen, and any obstructions or imperfections in the slit. These factors can alter the diffraction pattern and may result in a slightly different angle measurement.