Question

Find coherence time , coherence length and frequency bandwidth for white light range 4×10^14Hz to 7.5×10^14Hz.

Answer 1

Answer:

3.5x10^14Hz

Explanation:

Answer 2

Two waves are coherent when there is no phase difference between them so there is a fixed relationship between both the waves .

The coherence length is given by

                      $I_{c}$ =λ$.^{2}$ / (2πΔλ)

Given λ = 4*$10^{14}$ Hz     and            Δλ = 3.5 *$10^{14}$ Hz  

Thus we get ,  $I_{c}$ =     $\frac{(4*10^{14})^{2} }{3.5*10^{14} }$2π

                              =   8 * $10^{14}$ / 21.98

                             = 0.3639 * $10^{14}$

                       $I_{c}$ = 36.39 * $10^{12}$ m

The coherence time is given by  $t_{c}$ is  $t_{c}$= $\frac{I_{c} }{c}$

                                   $t_{c}$= $\frac{I_{c} }{c}$  

                                      =  $\frac{36.39 * 10^{12} }{3*10^{8} }$

                                  $t_{c}$=  12.13 *$10^{4}$ sec

The coherence length is  $I_{c}$ = 36.39 * $10^{12}$ m and the coherence time is       $t_{c}$=  12.13 *$10^{4}$ sec