Question

Figure $\mathbf{27}\mathbf{.}\mathbf{55}$ shows the central part of the interference pattern for a pure wavelength of red light projected onto a double slit. The pattern is actually a combination of single slit and double slit interference. Note that the bright spots are evenly spaced. Is this a double slit or single slit characteristic? Note that some of the bright spots are dim on either side of the center. Is this a single slit or double slit characteristic? Which is smaller, the slit width or the separation between slits? Explain your responses.

Short answer

The double-slit interference pattern is distinguished by its evenly spaced bright spots and the single slit pattern is characterized by the absence of bright spots. The slit spacing is smaller than the slit width.

Step-by-step solution

Define wavelength

The distance between identical spots between two subsequent waves is computed using the wavelength attribute of a wave.

Explanation

The double-slit interference pattern is distinguished by its evenly spaced bright spots.

The single slit pattern is characterized by the absence of bright spots.

The slight gap is more than the slight breadth because the equally spaced bright spots are smaller. That is, the slit spacing is smaller than the slit width.