*Question E4B02:
What is the significance of voltmeter sensitivity expressed in ohms per volt?*  

*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*  

### AI Response: (may contain errors)  

The significance of voltmeter sensitivity expressed in ohms per volt relates to the input impedance of the voltmeter. Let's break down the correct answer and the other choices.

### Correct Answer: 
**A: The full scale reading of the voltmeter multiplied by its ohms per volt rating is the input impedance of the voltmeter.**

- **Explanation**: 
  - The input impedance of a voltmeter is crucial because it affects how much the voltmeter influences the circuit being measured. 
  - The sensitivity rating in ohms per volt indicates how many ohms of input impedance the voltmeter has for each volt of full-scale reading. 
  - Therefore, if you multiply the full-scale voltage reading (in volts) by the sensitivity (in ohms per volt), you get the input impedance (in ohms):
  
  $$Z_{in} = V_{fs} \times S$$
  
  where:
  - $Z_{in}$ = input impedance
  - $V_{fs}$ = full scale reading in volts
  - $S$ = sensitivity in ohms per volt

### Why the Other Choices are Incorrect:

**B: The reading in volts multiplied by the ohms per volt rating will determine the power drawn by the device under test.**

- **Explanation**: 
  - This statement is incorrect because it confuses voltage with power. Power ($P$) is calculated using the formula:
  
  $$P = \frac{V^2}{R}$$
  
  where $R$ is the resistance. Simply multiplying voltage by ohms per volt does not yield power.

**C: The reading in ohms divided by the ohms per volt rating will determine the voltage applied to the circuit.**

- **Explanation**: 
  - This statement is also incorrect. The relationship described does not yield voltage. The voltage applied to a circuit is independent of the ohms per volt rating. The correct relationship involves the input impedance and the current flowing through the circuit.

**D: The full scale reading in amps divided by ohms per volt rating will determine the size of shunt needed.**

- **Explanation**: 
  - This statement is misleading. The size of a shunt resistor is determined by the current to be measured and the voltage drop across the shunt, not directly by the ohms per volt rating of a voltmeter. The shunt calculation involves the full-scale current and the desired voltage drop across the shunt.

### Summary:
- The correct answer emphasizes the relationship between the voltmeter's full-scale reading and its input impedance, which is essential for accurate measurements in circuits. Understanding these concepts is vital for effective use of voltmeters in amateur radio and other electronic applications.