How is a voltmeter connected to a component to measure applied voltage?
The correct answer is B: In parallel. A voltmeter is connected in parallel to a component to measure applied voltage. Parallel connection means the voltmeter is connected across (on both sides of) the component, allowing it to measure the voltage difference between those two points. This is different from series connection, where components are connected end-to-end. For amateur radio operators, understanding parallel connection is essential for proper voltage measurement. Connecting a voltmeter in series would break the circuit and give incorrect readings. Parallel connection doesn't affect the circuit operation significantly because voltmeters have very high input impedance.
Exam Tip
Voltmeter = parallel connection. Think 'V'oltmeter = 'V'oltage across = 'P'arallel. Voltmeters connect across (parallel to) components to measure voltage difference. Series connection would break the circuit.
Memory Aid
"Voltmeter = Parallel connection. Think 'V'oltmeter = 'V'oltage across = 'P'arallel. Connects across components to measure voltage difference."
Real-World Application
To measure the voltage across a resistor, you connect the voltmeter's probes to both ends of the resistor (parallel connection). The voltmeter measures the voltage difference between these two points without significantly affecting the circuit. If you connected it in series, you'd break the circuit and get no reading.
Key Concepts
Why Other Options Are Wrong
Option A (In series): Incorrect. Connecting a voltmeter in series would break the circuit and prevent current flow. Voltmeters measure voltage across components, not through them.
Option C (In quadrature): Incorrect. Quadrature refers to a 90-degree phase relationship, not a connection method. This isn't a valid connection type for voltmeters.
Option D (In phase): Incorrect. 'In phase' refers to signals having the same phase, not a connection method. This isn't how voltmeters are connected.
题目解析
The correct answer is B: In parallel. A voltmeter is connected in parallel to a component to measure applied voltage. Parallel connection means the voltmeter is connected across (on both sides of) the component, allowing it to measure the voltage difference between those two points. This is different from series connection, where components are connected end-to-end. For amateur radio operators, understanding parallel connection is essential for proper voltage measurement. Connecting a voltmeter in series would break the circuit and give incorrect readings. Parallel connection doesn't affect the circuit operation significantly because voltmeters have very high input impedance.
考试技巧
Voltmeter = parallel connection. Think 'V'oltmeter = 'V'oltage across = 'P'arallel. Voltmeters connect across (parallel to) components to measure voltage difference. Series connection would break the circuit.
记忆口诀
Voltmeter = Parallel connection. Think 'V'oltmeter = 'V'oltage across = 'P'arallel. Connects across components to measure voltage difference.
实际应用示例
To measure the voltage across a resistor, you connect the voltmeter's probes to both ends of the resistor (parallel connection). The voltmeter measures the voltage difference between these two points without significantly affecting the circuit. If you connected it in series, you'd break the circuit and get no reading.
错误选项分析
Option A (In series): Incorrect. Connecting a voltmeter in series would break the circuit and prevent current flow. Voltmeters measure voltage across components, not through them. Option C (In quadrature): Incorrect. Quadrature refers to a 90-degree phase relationship, not a connection method. This isn't a valid connection type for voltmeters. Option D (In phase): Incorrect. 'In phase' refers to signals having the same phase, not a connection method. This isn't how voltmeters are connected.
知识点
Voltmeter connection, Parallel connection, Voltage measurement, Circuit measurement
Verified Content
Question from official FCC Technician Class question pool. Explanation reviewed by licensed amateur radio operators.