Two towers on the top of two hills are 40 km apart. The line joining them presses 50 m above a hill half way between the towers. What is the longest wavelength of radiowaves which can be send between the towers without apprecialbe fiffraction effects?

Options

A. 1.25 m
B. 0.125 m
C. 2.50 m
D. 0.250 m

Answer

B

Explanation

Distance between one of the towers and hill half way `= 40//2km=2xx10^(4) km`
` :. z_(F)=2xx10^(4)km`
Using, ` :. z_(F)=(a^(2))/(lambda) " or " lambda=(a^(2))/(z_(F))`
` :. lambda=((50)^(2))/(2xx10^(4))=1250xx10^(-4)=0.125m`