ARRL Technician Practice Exam

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Prepare for the ARRL Technician Exam. Access flashcards and multiple choice questions with detailed explanations. Get ready to become a certified amateur radio operator!

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What is the formula used to calculate electrical power in a DC circuit?

Power (P) equals current (I) divided by voltage (E)
Power (P) equals voltage (E) multiplied by current (I)
Power (P) equals voltage (E) plus current (I)
Power (P) equals resistance (R) times current (I)

The correct answer is: Power (P) equals voltage (E) multiplied by current (I)

The formula that accurately represents the calculation of electrical power in a DC circuit is given by Power (P) equals voltage (E) multiplied by current (I). This relationship is grounded in Ohm’s law, which establishes that the power consumed in an electrical circuit is the product of the voltage across the circuit and the current flowing through it. In mathematical terms, the equation is expressed as P = E × I, where P is power measured in watts, E is voltage in volts, and I is current in amperes. This formula is fundamental in electrical engineering and is routinely used to determine how much power a device or a circuit will consume or require. The other options do not reflect the correct relationship for calculating power. The formula involving resistance times current misrepresents power as resistance does not directly correlate to energy consumed; instead, it relates to Ohm's law (V = I × R). The division of current by voltage does not yield power either, and the sum of current and voltage does not provide any meaningful calculation in this context. Thus, the multiplication of voltage and current is essential to correctly ascertain the power in a DC circuit.