(a) Describe briefly three factors which justify the need for modulation of audio frequency signals over long distances in communication .
(b) Draw the waveforms of (i) carrier wave , (ii) a modualating signal and , (iii) amplitude modulated wave.

Explanation

### Solution:

**(a) Three Factors Justifying the Need for Modulation of Audio Frequency Signals Over Long Distances in Communication:**

1. **Size of Antenna:**
- The size of the antenna or aerial is directly related to the wavelength of the signal being transmitted. For effective transmission, the length of the antenna should ideally be a quarter of the wavelength (λ/4). Since audio frequency signals have long wavelengths, the antennas required for such frequencies would be impractically large. Modulation allows the use of higher frequency carrier waves, which can be transmitted using smaller antennas.

2. **Effective Power Radiated:**
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