Modern Physics 7 Question 78

8. The physical sizes of the transmitter and receiver antenna in a communication system are

(Main 2019, 9 April II)

(a) proportional to carrier frequency

(b) inversely proportional to modulation frequency

(c) independent of both carrier and modulation frequency

(d) inversely proportional to carrier frequency

Show Answer

Solution:

  1. Size of antenna is directly proportional to the wavelength of the signal.

Also, the speed at which signal moves =carrier frequency $\times$ wavelength

$$ \begin{aligned} & \Rightarrow \quad f \lambda=c \Rightarrow \lambda \propto \frac{1}{f} \\ & \therefore \text { Size of antenna } \propto \frac{1}{f} . \end{aligned} $$

NOTE Minimum size of the antenna is $\lambda / 4$.



जेईई के लिए मॉक टेस्ट

एनसीईआरटी अध्याय वीडियो समाधान

दोहरा फलक