Amplitude modulation is the process of

Options

A. superimposing a high frequency signal on a high frequency carrier signal
B. superimposing a low frequency signal on a high frequency carrier signal
C. single sideband communication
D. amplitude shift and phase shift

Answer

### Step-by-Step Solution:

1. **Understanding Amplitude Modulation (AM)**:
- Amplitude modulation is a technique used in electronic communication, most commonly for transmitting information via a radio carrier wave. In AM, the amplitude (signal strength) of the carrier wave is varied in proportion to that of the message signal being sent.

2. **Identifying the Components**:
- The process involves two main signals:
- A **low-frequency message signal** (the information you want to transmit).
- A **high-frequency carrier signal** (the wave that carries the information).

3. **Analyzing the Options**:
- The question provides four options regarding the definition of amplitude modulation. We need to evaluate each option to determine which one accurately describes the process.

4. **Evaluating Option 1**:
- **Option 1**: "Superimposing high frequency signal on high frequency carrier signal."
- This option is incorrect because amplitude modulation involves a low-frequency signal, not a high-frequency one.

5. **Evaluating Option 2**:
- **Option 2**: "Superimposing a low frequency signal on a high carrier signal."
- This option is correct. In amplitude modulation, the low-frequency message signal is indeed superimposed on the high-frequency carrier signal.

6. **Evaluating Option 3**:
- **Option 3**: "Single side by side communication has no sense."
- This option does not accurately describe amplitude modulation and is therefore incorrect.

7. **Evaluating Option 4**:
- **Option 4**: "Amplitude shift and phase shift."
- This option is also incorrect as it does not capture the essence of amplitude modulation, which specifically involves varying the amplitude of a carrier wave based on a low-frequency signal.

8. **Conclusion**:
- The correct definition of amplitude modulation is given by **Option 2**: "Superimposing a low frequency signal on a high carrier signal."