Deep Dive: E4B02
The correct answer is A: The full scale reading of the voltmeter multiplied by its ohms per volt rating is the input impedance of the voltmeter. What is the significance of voltmeter sensitivity expressed in ohms per volt is that the full scale reading multiplied by ohms per volt rating equals the input impedance. Ohms per volt allows calculation of input impedance. For amateur radio operators, this is important for test equipment. Understanding this helps when using voltmeters.
Why Other Answers Are Wrong
Option B: Incorrect. Reading in volts multiplied by ohms per volt doesn't determine power drawn - full scale multiplied by ohms per volt equals input impedance. Power drawn isn't the significance. Option C: Incorrect. Reading in ohms divided by ohms per volt doesn't determine voltage - full scale multiplied by ohms per volt equals input impedance. Voltage determination isn't the significance. Option D: Incorrect. Full scale in amps divided by ohms per volt doesn't determine shunt size - full scale multiplied by ohms per volt equals input impedance. Shunt size isn't the significance.
Exam Tip
Voltmeter ohms per volt significance = full scale reading × ohms per volt = input impedance. Think 'O'hms 'P'er 'V'olt = 'O'utput 'P'erformance 'V'alue (input impedance). Ohms per volt allows calculation of input impedance. Not power drawn, not voltage, not shunt size - just input impedance.
Memory Aid
Voltmeter ohms per volt significance = full scale reading × ohms per volt = input impedance. Think 'O'hms 'P'er 'V'olt = 'I'nput 'I'mpedance. Ohms per volt allows calculation of input impedance. Important for test equipment.
Real-World Example
Voltmeter sensitivity in ohms per volt: The full scale reading of the voltmeter multiplied by its ohms per volt rating equals the input impedance. For example, a 10V full scale meter with 20,000 ohms per volt has 200,000 ohms input impedance. This is the significance - full scale × ohms per volt = input impedance.
Source & Coverage
Question Pool: 2024-2028 Question Pool
Subelement: E4B
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 E4B topic.