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A slit of width is illuminated by white light. For red light `(lambda=6500Å)`, the first minima is obtained at `theta=30^@`. Then the value of will beA. `3250Å`B. `6.5 xx 10^(-4)cm`C. `1.3` micronD. `2.6 xx 10^(-4)cm` |
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Answer» Correct Answer - C `sin theta = (n lambda)/(a)`, for `n =1, sin theta = (lambda)/(a)` `:. a = (lambda)/(sin theta) = (6500 xx 10^(-10))/(sin 30^(@))` `a = 13000 xx 10^(-10)m` `a = 1.3 xx 10^(-6)m` `a = 1.3` micron |
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