*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 what power level a receiver minimum discernible signal of -100 dBm represents, we need to convert from dBm to watts.

### Explanation:

1. **Understanding dBm:**
   - dBm is a unit of power relative to 1 milliwatt (mW).
   - The formula to convert dBm to watts is:
     $$ P(\text{watts}) = 10^{\frac{P(\text{dBm})}{10}} \times 10^{-3} $$

2. **Calculation for -100 dBm:**
   - Substitute -100 dBm into the formula:
     $$ P(\text{watts}) = 10^{\frac{-100}{10}} \times 10^{-3} $$
   - Simplify the exponent:
     $$ P(\text{watts}) = 10^{-10} \times 10^{-3} $$
   - Combine the powers of 10:
     $$ P(\text{watts}) = 10^{-13} \text{ watts} $$

3. **Convert to picowatts:**
   - 1 watt = $10^{12}$ picowatts
   - Therefore, $10^{-13}$ watts = $10^{-13} \times 10^{12}$ picowatts = 0.1 picowatts

### Correct Answer:
- **D: 0.1 picowatts** is correct because -100 dBm converts to 0.1 picowatts.

### Why Other Choices Are Incorrect:
- **A: 100 microwatts** is incorrect because 100 microwatts is $10^{-4}$ watts, which corresponds to -10 dBm, not -100 dBm.
- **B: 0.1 microwatt** is incorrect because 0.1 microwatt is $10^{-7}$ watts, which corresponds to -70 dBm, not -100 dBm.
- **C: 0.001 microwatts** is incorrect because 0.001 microwatts is $10^{-9}$ watts, which corresponds to -90 dBm, not -100 dBm.

By understanding the conversion from dBm to watts and then to picowatts, you can accurately determine the power level represented by a given dBm value.