In Young's double slit experiment, one of the slit is wider than other, so that amplitude of the light from one slit is double of that from other slit. If \[{{I}_{m}}\] be the maximum intensity, the resultant intensity \[I\] when they interfere at phase difference \[\phi \] is given by

• A. \[\frac{{{I}_{m}}}{9}(4+5cos\phi )\]
• B.        \[\frac{{{I}_{m}}}{3}\left( 1+2co{{s}^{2}}\frac{\phi }{2} \right)\]
• C. \[\frac{{{I}_{m}}}{5}\left( 1+4co{{s}^{2}}\frac{\phi }{2} \right)\]
• D.        \[\frac{{{I}_{m}}}{9}\left( 1+8co{{s}^{2}}\frac{\phi }{2} \right)\]