1 files changed, 15 insertions, 0 deletions
diff --git a/728/CH4/EX4.8/Ex4_8_ans.txt b/728/CH4/EX4.8/Ex4_8_ans.txt
new file mode 100755
index 000000000..02d1dd212
--- /dev/null
+++ b/728/CH4/EX4.8/Ex4_8_ans.txt
@@ -0,0 +1,15 @@
+ Cut-off wavelength (in cm) =   
+ 
+    20.  
+ 
+ Guide wavelength (in cm) =   
+ 
+    15.  
+ 
+ Phase velocity (in cm/s) =   
+ 
+    3.750D+10  
+ 
+ Group velocity (in cm/s) =   
+ 
+    2.400D+10