Question

the intensity of a light pulse travelling along an optical fibre decreases exponentially with distance according to the relation I = I₀e^-0.0693x where x is in km and I₀ is intensity of incident pulse. The intensity of pulse reduces to 1/4 after travelling a distance

(1) 1km

(2) 10km

(3) 20km

(4) 40km

Answer 1

3) 20 km is the answere

Answer 2

Answer:

20km

Explanation:

take I to be I•/4

and then antilog you will get the answer