The number of telephone conversations by a fibre of band width 40MHz, with much less intensity loss, are:

Options

A. 1800
B. 2000
C. 2200
D. 2400

Answer

To determine the number of telephone conversations that a fiber optic cable with a bandwidth of 40 MHz can support, we can follow these steps:

### Step-by-Step Solution:

1. **Understand Bandwidth and Data Rate**:
- The bandwidth of the fiber is given as 40 MHz. Bandwidth is a measure of the maximum data transfer rate of a network or internet connection.

2. **Determine Data Rate**:
- For fiber optics, a rough estimate is that each MHz of bandwidth can carry approximately 1 Mbps (megabit per second) of data. Therefore, for a bandwidth of 40 MHz:
\[ \text{Data Rate} = 40 \text{ MHz} \times 1 \text{ Mbps/MHz} = 40 \text{ Mbps} \]

3. **Calculate the Number of Conversations**:
- A typical voice call requires about 64 Kbps (kilobits per second). To find out how many simultaneous calls can be supported by the fiber:
\[ \text{Number of Conversations} = \frac{\text{Data Rate}}{\text{Data Rate per Call}} = \frac{40 \text{ Mbps}}{64 \text{ Kbps}} \]
- First, convert 40 Mbps to Kbps:
\[ 40 \text{ Mbps} = 40,000 \text{ Kbps} \]
- Now, calculate the number of conversations:
\[ \text{Number of Conversations} = \frac{40,000 \text{ Kbps}}{64 \text{ Kbps}} \approx 625 \]

4. **Conclusion**:
- Therefore, a fiber optic cable with a bandwidth of 40 MHz can support approximately 625 simultaneous telephone conversations with minimal intensity loss.

### Final Answer:
The number of telephone conversations that a fiber with a bandwidth of 40 MHz can carry is approximately **625**.