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 solve the problem of determining the number of telephone conversations that can be supported by a fiber optic cable with a bandwidth of 40 MHz, we can follow these steps:

### Step 1: Understand the Bandwidth
The bandwidth of the fiber optic cable is given as 40 MHz. Bandwidth is a measure of the maximum data transfer rate of a network or internet connection.

### Step 2: Determine the Data Rate
For telecommunication systems, a common rule of thumb is that each telephone conversation requires a certain amount of bandwidth. For traditional voice calls, it is often approximated that each call requires about 64 kbps (kilobits per second).

### Step 3: Convert Bandwidth to Bits per Second
To find out how many conversations can be supported, we first need to convert the bandwidth from MHz to bits per second:
- 1 MHz = 1,000,000 Hz
- Therefore, 40 MHz = 40 x 1,000,000 Hz = 40,000,000 Hz

Since 1 Hz can be used to transmit 1 bit per second, we have:
- Bandwidth in bits per second = 40,000,000 bps (bits per second)

### Step 4: Calculate the Number of Conversations
Now, we can calculate the number of simultaneous telephone conversations that can be supported:
- Each conversation requires approximately 64 kbps = 64,000 bps.
- Number of conversations = Total bandwidth / Bandwidth per conversation
- Number of conversations = 40,000,000 bps / 64,000 bps

### Step 5: Perform the Calculation
Now we perform the calculation:
- Number of conversations = 40,000,000 / 64,000 = 625

### Step 6: Conclusion
Thus, the number of telephone conversations that can be supported by a fiber optic cable with a bandwidth of 40 MHz is approximately 625.

### Final Answer:
The number of telephone conversations by a fiber of bandwidth 40 MHz is approximately **625**.

---