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Wave Optics — Physics STD 12 Science — Question

Gujarat BoardEnglish MediumSTD 12 SciencePhysicsWave Optics3 Marks
Question
In Young’s double slit experiment, explain with reason in each case, how the interference pattern changes, when :
  1. Width of the slits is doubled.
  2. Separation between the slits is increased.
  3. Screen is moved away from the plane of slits.
✓

Answer

  1. The fringe width $\beta= \frac{\text{D}\lambda}{\text{d}}.$
  2. When the width of the slit is doubled; the intensity of interfering waves becomes four times, intensity of maxima becomes 16 times i.e., fringes become brighter.
  3. When separation between the slits is increased the fringe width decreases, i.e., fringes come closer.
  4. $\beta \alpha\text {D }$ when screen is moved away from the plane of the slits, the fringe width increases, i.e., fringes become farther away.

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