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Please help! - Optics - NEET

A beam of light \lambda =600 nm from a distant source falls on a single slit 1 mm wide and the resulting diffraction pattern is observed on a screen 2 m away. The distance between first dark fringes on either side of the central bright fringe is:

  • Option 1)

    1.2 cm

  • Option 2)

    1.2 mm

  • Option 3)

    2.4 cm

  • Option 4)

    2.4 mm

 
Answers (1)
102 Views
V Vakul

As we learnt in

Fraunhofer Diffraction -

bsin 	heta = nlambda
 

- wherein

Condition of nth minima.

b= slit width

	heta = angle of deviation

 

 distance between first daic fringe on both side means width of central maxima 

\therefore\Delta y = \frac{2\lambda D}{b}=\frac{2\times600\times10^{-9}\times2m}{10^{-3}m}

\Deltay=2.4mm


Option 1)

1.2 cm

This is incorrect option 

Option 2)

1.2 mm

This is incorrect option 

Option 3)

2.4 cm

This is incorrect option 

Option 4)

2.4 mm

This is correct option 

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