We do not transmit low frequency signal to long distances because
(a) The size of the antenna should be comparable to signal wavelength which is unreal solution for a signal of longer wavelength.
(b) Effective power radiated by a long wavelength baseband signal would be high.
(c) We want to avoid mixing up signals transmitted by different transmitter simultaneously.
(d) Low frequency signal can be sent to long distances by superimposing with a high frequency wave as well.
Therefore, the most suitable options will be :
(a) The size of the antenna should be comparable to signal wavelength which is unreal solution for a signal of longer wavelength.
(b) Effective power radiated by a long wavelength baseband signal would be high.
(c) We want to avoid mixing up signals transmitted by different transmitter simultaneously.
(d) Low frequency signal can be sent to long distances by superimposing with a high frequency wave as well.
Therefore, the most suitable options will be :
- (A)All statements are true
- (B)(a), (b) and (c) are true only
- (C)(a), (c) and (d) are true only✓ Correct
- (D)(b), (c) and (d) are true only
Answer: (C)
Solution
Let's analyze each statement:
(a) True: For efficient transmission, antenna size should be comparable to wavelength (). Low frequency signals have very long wavelengths, requiring impractically large antennas.
(b) False: Effective power radiated (EPR) is low for long wavelength signals, not high. Power radiated is proportional to , so longer wavelengths radiate less efficiently.
(c) True: To avoid interference and mixing of signals from different transmitters, we use modulation with different carrier frequencies.
(d) True: Low frequency signals are transmitted long distances by modulating them onto high frequency carrier waves (amplitude/frequency modulation).
Therefore, statements (a), (c), and (d) are true.
(a) True: For efficient transmission, antenna size should be comparable to wavelength (). Low frequency signals have very long wavelengths, requiring impractically large antennas.
(b) False: Effective power radiated (EPR) is low for long wavelength signals, not high. Power radiated is proportional to , so longer wavelengths radiate less efficiently.
(c) True: To avoid interference and mixing of signals from different transmitters, we use modulation with different carrier frequencies.
(d) True: Low frequency signals are transmitted long distances by modulating them onto high frequency carrier waves (amplitude/frequency modulation).
Therefore, statements (a), (c), and (d) are true.
JEE Main · 2022 · 27 Jun 2022 · Shift 2 · Single correct option