Your friend has been given a laser for her birthday. Unfortunately, she did not receive a manual with it and so she doesn’t know the wavelen

Question

Your friend has been given a laser for her birthday. Unfortunately, she did not receive a manual with it and so she doesn’t know the wavelength that it emits. You help her by performing a double-slit experiment, with slits separated by 0.18 mmmm. You find that two adjacent bright fringes are 4.9 mmmm apart on a screen 1.4 mm from the slits.

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Bình An 4 years 2021-07-29T20:16:49+00:00 2 Answers 27 views 0

Answers ( )

  1. bonexptip
    0
    2021-07-29T20:18:20+00:00
    Reply

    Answer:

    \lambda=630 nm        

    Explanation:

    The equation of the fringe in a double slit experiment is given by:

    y=\frac{m\lambda D}{d} (1)

    here:

    • y is the distance between bright fringes (two adjacent bright fringes distance = 4.9 mm).
    • m is a natural number, related to the bright fringes in a diffraction pattern, in our case we use m=1
    • D is the distance between the screen and the double slit (D=1.4 m)
    • d is the distance between the slits (d=0.18 mm)
    • λ is the wave length of the laser.

    Therefor we just need to solve the equation (1) for λ:

    \lambda=\frac{d*y}{D}

    \lambda=\frac{0.00018*0.0049}{1.4}            

    \lambda=6.3*10^{-7}m      

    \lambda=630 nm        

    I hope it helps you!                              

  2. Xavia
    0
    2021-07-29T20:18:27+00:00
    Reply

    Answer:

    6.3*10^-7m

    Explanation:

    to find the wavelength of the laser you can use the following formula:

    y=\frac{m\lambda D}{d}

    y: height from the center of the screen to a fringe

    m: order of the fringe

    D: distance to the screen = 1.4m

    d: distance between slits = 0.18mm

    you know the separation of two fringes. Hence, you can use two consecutive fringes to find the wavelength in the following way:

    \Delta y=\frac{m\lambda D}{d}-\frac{(m-1)\lambda D}{d}=\frac{\lambda D }{d}\\\\\lambda=\frac{\Delta y d}{D}=\frac{(4.9*10^{-3}m)(0.18m*10^{-3}m)}{1.4m}=6.3*10^{-7}m

    hence, the walength is 6.3*10^-7m

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