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The intensity of light pulse travelling in an optical fiber decreases according to the relation `I=I_(0)e^(-alpha x)` . The intensity of light is reduced to `20%` of its initial value after a distance x equal toA. In`((1)/(alpha))`B. In`(alpha)`C. `(("In"5))/(alpha)`D. In `((5)/(alpha))` |
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Answer» Correct Answer - C `(I)/(I_(0)) = e^(-alpha x) = (20)/(100) = e^(alpha x) = 5` `ax = log_(e) 5, x=(("In" 5))/(alpha)` OR `I=I_(0)e^(-alpha x)` `0.2 I_(0) = I_(0) e^(-alpha x) ` `(2)/(10) = e^(-alpha x) rArr (10)/(2) = e^(alpha x)` `l n(5) = dx` `x=(l n(5)J)/(alpha) ` |
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