Deep Dive: E4D14
The correct answer is D: 0.1 picowatts. What power level does a receiver minimum discernible signal of -100 dBm represent is 0.1 picowatts. -100 dBm = 10^-13 W = 0.1 × 10^-12 W = 0.1 picowatts. For amateur radio operators, this is important for understanding signal levels. Understanding this helps when evaluating receivers.
Why Other Answers Are Wrong
Option A (100 microwatts): Incorrect. 100 microwatts is way too high - -100 dBm = 0.1 picowatts. 100 microwatts is wrong. Option B (0.1 microwatts): Incorrect. 0.1 microwatts is too high - -100 dBm = 0.1 picowatts. 0.1 microwatts is wrong. Option C (0.001 microwatts): Incorrect. 0.001 microwatts is still too high - -100 dBm = 0.1 picowatts. 0.001 microwatts is wrong.
Exam Tip
MDS -100 dBm = 0.1 picowatts. Think '-1'00 dBm = '0'.1 'P'icowatts. -100 dBm = 10^-13 W = 0.1 × 10^-12 W = 0.1 picowatts. Not 100 microwatts, not 0.1 microwatts, not 0.001 microwatts - just 0.1 picowatts.
Memory Aid
MDS -100 dBm = 0.1 picowatts. Think '-1'00 dBm = '0'.1 'P'icowatts. -100 dBm = 10^-13 W = 0.1 picowatts. Important for understanding signal levels.
Real-World Example
A receiver minimum discernible signal of -100 dBm: It represents 0.1 picowatts. -100 dBm = 10^-13 watts = 0.1 × 10^-12 watts = 0.1 picowatts. This is an extremely small power level. This is the power level - 0.1 picowatts.
Source & Coverage
Question Pool: 2024-2028 Question Pool
Subelement: E4D
Reference: 2024-2028 Question Pool · E4 - Amateur Practices
Key Concepts
Verified Content
Question from the official FCC Extra Class pool. Explanation reviewed by licensed amateur radio operators and mapped to the E4D topic.