The Total solution for NCERT class 6-12
Which of the followingfrequencies will be suitable for beyond-the-horizoncommunication using sky waves?
(a) 10 kHz
(b) 10 MHz
(c) 1 GHz
(d) 1000 GHz
(b)Answer:
10 MHz
For beyond-the-horizoncommunication, it is necessary for the signal waves to travel a large distance.10 KHz signals cannot be radiated efficiently because of the antenna size. Thehigh energy signal waves (1GHz − 1000 GHz) penetrate the ionosphere. 10 MHz frequenciesget reflected easily from the ionosphere. Hence, signal waves of suchfrequencies are suitable for beyond-the-horizon communication.