Two beams of light having intensities I and 4I interfere to produce a fringe pattern on a screen. The phase difference between the two beams are $\pi / 2$ and $\pi / 3$ at points $\mathrm{A}$ and $\mathrm{B}$ respectively. The difference between the resultant intensities at the two points is $x I$. The value of $x$ will be ________.
Answer (integer)
2
Solution
<p>${I_{{R_1}}} = {I_1} + {I_2} + 2\sqrt {{I_1}{I_2}} \cos \phi$</p>
<p>${I_A} = I + 4I + 2\sqrt {I.4I} \cos 90^\circ$</p>
<p>$= 5I$</p>
<p>${I_B} = I + 4I + 2\sqrt {I.4I} \cos 60^\circ$</p>
<p>$= 7I$</p>
<p>${I_B} - {I_A} = 2I$</p>
About this question
Subject: Physics · Chapter: Optics · Topic: Reflection and Mirrors
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