208
Question
The intensity falls as we move to successive maxima away from the centre on either side.
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Solution
Consider a monochromatic beam of light incident on a slit of width a. Interference occurs between the light that passes through different parts of the slit, resulting in what is called a diffraction pattern. Viewed on a distant screen, the diffraction pattern consists of alternating bright and dark interference fringes.
According to Huygen's principle, each portion of the slit acts as a source of light waves.Hence, light from one portion of slit can interfere with lights of other portion, and the resultant intensity depends on the direction, θ.
Phasors can be used to determine light intensity distribution. Each zone slit is divided into, contributes to electric field at a point on the screen. Square of total sum of magnitudes of these fields is proportional to the intensity at that point.
Final result is an angle dependent equation for intensity which is maximum at θ=0, i.e. at the centre. As we move away, it decreases. Attached figure shows the variation.
According to Huygen's principle, each portion of the slit acts as a source of light waves.Hence, light from one portion of slit can interfere with lights of other portion, and the resultant intensity depends on the direction, θ.
Phasors can be used to determine light intensity distribution. Each zone slit is divided into, contributes to electric field at a point on the screen. Square of total sum of magnitudes of these fields is proportional to the intensity at that point.
Final result is an angle dependent equation for intensity which is maximum at θ=0, i.e. at the centre. As we move away, it decreases. Attached figure shows the variation.
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