Figure 1 shows schematically an arrangement for producing interference fringes using a double slit.
There are two slits at points A and B and a bright fringe (maximum intensity) is observed at the point labelled P.
Explain how the path difference determines that the light intensity at point P is a maximum.
The light source has a wavelength of 45 mm.
The distance from A to P = 1.13 m and from B to P is 1.40 m.
Show that the light intensity at point P is a maximum.
The light source used in Figure 1 is monochromatic but not coherent.
Explain the purpose of the single slit to observe clear interference fringes.
In another double slit experiment, the separation of the slits is 6.3 × 10–4 m. The distance from the slits to the screen is 0.45 m.
Calculate the distance between the centres of two adjacent bright fringes when light of wavelength 780 nm is used.
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