Write three important factors which justify the need of modulating a message signal.
Show diagrammatically how an amplitude modulated wave is obtained when a modulating signal is superimposed on a carrier wave.

Explanation

### Step-by-Step Solution:

#### Part 1: Factors Justifying the Need for Modulating a Message Signal

1. **Practical Size of Antenna**:
- The size of the antenna is directly related to the wavelength of the signal being transmitted. For lower frequency signals, the wavelength is longer, which requires larger antennas. Modulation allows the transmission of higher frequency signals, which can be accommodated by smaller antennas.

2. **Effective Power Radiated by an Antenna**:
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