Single Slit Diff

USER MAUAL FOR : SIGLE SLIT DIFFRACTIO EXPERIMET AIM: - To determine the wavelength of the given source using a single slit. APPARATUS: - Single slit, spectrometer, microscope and sodium sources. THEORY: When collimated light is incident on a single slit, of width a, diffraction takes place and result in a pattern consisting of bright and dark intensities. Wavelength of the sources is then related to the minima of this diffraction pattern according to the following equation. a sin θ = n λ Where n is the order of diffraction (n= ±1, ±2, ±3-------) λ is the wavelength of the source a is the slit width θ is the angle of diffraction. The maximum of the diffraction are found at points satisfying the following equation Tan β=β Where β= π a sin θ λ

DIAGRAM: C

SLIT

Left side

T T Direct Reading

T

Right side

PROCEDURE: 1) Adjust the collimator of the spectrometer to get a parallel beam of light .The telescope has to be adjusted to see the collimated light coming from the collimator. 2) Place the single slit on the prism table and fix it with screws. Adjust the slit width using the screw attached to it so as to observe a diffraction pattern through the telescope. 3) Find the angle (2θ) between the two same order (n) minima of diffraction beams using Spectrometer. 4) Determine the width of the slit using a microscope. 5) Substituting the values of n, θ and a in equation one can determine the wavelength of the given source. 6) Repeat the experiment with different orders of minima of diffraction beams and with slit widths.

1

OBSERVATIO TABLE: Determination of slit width: -

Sr.no

Microscope readings Left

Slit

Right

Width

Determination of θ: Order of minima n

Spectrometer reading Left minimum Right minimum V1

V2

V1

1

V

2

2θ V1-V11 V2 – V21 Mean 2θ

1

RESULT: - Wavelength of the given source.

2

θ

λ