Coast Guard Exams
Question 329Electricity/Electronics - QMED70% to pass

An internal resistance is placed in series with the meter movement of which of the following instruments?

AI Explanation
The correct answer is A) DC voltmeter. In a DC voltmeter, an internal resistance is placed in series with the meter movement to limit the current flowing through the meter and protect it from damage due to high voltages. This internal resistance, also known as a multiplier resistor, allows the voltmeter to measure a wide range of voltages by scaling the input voltage to a level that the meter movement can safely handle. The other options are incorrect because an AC ammeter, AC frequency meter, and DC ammeter do not require an internal resistance in series with the meter movement. Ammeters measure current directly, while AC frequency meters typically use a different mechanism to measure frequency, such as a zero-crossing detector.