*Question E4D14:
What power level does a receiver minimum discernible signal of -100 dBm represent?*  

*Correct Answer is  D: 0.1 picowatts*  

### AI Response: (may contain errors)  

To determine the power level that a receiver's minimum discernible signal of -100 dBm represents, we need to convert the dBm value to watts.

### Conversion from dBm to Watts
The formula to convert dBm to watts is:

$$
P(W) = 10^{(P(dBm) - 30)/10}
$$

Where:
- $P(W)$ = power in watts
- $P(dBm)$ = power in dBm

### Calculation
For -100 dBm:

$$
P(W) = 10^{(-100 - 30)/10} = 10^{-13} = 0.0000000001 \text{ W} = 0.1 \text{ microwatts}
$$

However, we need to express this in picowatts:

1 microwatt (µW) = 1000 picowatts (pW), so:

$$
0.1 \text{ µW} = 0.1 \times 1000 \text{ pW} = 100 \text{ pW}
$$

Thus, -100 dBm corresponds to 100 picowatts, not 0.1 picowatts. 

### Correct Answer
The correct answer is **0.1 microwatts**, which is equivalent to **100 picowatts**. 

### Explanation of Choices
- **A: 100 microwatts**  
  This is incorrect because it is 1000 times larger than the correct value.
  
- **B: 0.1 microwatt**  
  This is incorrect because it is 10 times larger than the correct value.
  
- **C: 0.001 microwatts**  
  This is incorrect because it is 100 times smaller than the correct value.
  
- **D: 0.1 picowatts**  
  This is incorrect because it is 1000 times smaller than the correct value.

### Summary
- The minimum discernible signal of -100 dBm corresponds to **0.1 microwatts** or **100 picowatts**.
- The conversion from dBm to watts is crucial for understanding power levels in radio communications.