A diffraction pattern is formed on a screen 130 cm away from a 0.420-mm-wide slit. Monochromatic 546.1-nm light is used. Calculate the fractional intensity I/Imax at a point on the screen 4.10 mm from the center of the principal maximum.

Respuesta :

Answer:

The fractional Intensity [tex]\frac{I}{I_{max}}[/tex] = 0.0146

Given:

wavelength of the light, [tex]\lambda = 546.1 nm = 546.1\times 10^{-9} m[/tex]

slit and screen separation difference, D = 130 cm = 1.3 m

distance of the point from the center of the principal maximum, y = 4.10 mm = 0.041 m

slit width, d = 0.420 mm = [tex]0.420\times 10^{-3}[/tex]

Solution:

To calculate the fractional intensity, we use the given formula:

[tex]\frac{I}{I_{max}} = \frac{sin^{2}\delta }{\frac({\delta}{2})^{2}}[/tex]             (1)

[tex]\delta = \frac{\pi }{\lambda}dsin\theta [/tex]    

For very small angle:                                        

[tex]\delta = \frac{\pi dy}{\lambda D}[/tex]                                  (2)

where

[tex]\delta = total phase angle [/tex]

[tex]\theta = angle of deviation[/tex]

Using eqn (2):

[tex]\delta = \frac{\pi \times 0.42\times 10^{-3}\times 4.1\times 10^{-3} }{546.1\times 10^{-9}\times 1.3} = 7.6202 radians[/tex]

Now, using eqn (1):

[tex]\frac{I}{I_{max}} = \frac{sin^{2}(7.6202) }{(\frac{7.6202}{2})^{2}} = 0.0146[/tex]