At constant voltage, doubling the resistance halves the current. What is the correct statement?

The correct statement is that at constant voltage, doubling the resistance does indeed halve the current. This principle is derived from Ohm's Law, which states that the current (I) flowing through a conductor between two points is directly proportional to the voltage (V) across the two points and inversely proportional to the resistance (R). Mathematically, this is expressed as I = V/R.

When the voltage remains constant and you double the resistance, you are effectively increasing the denominator in this equation. As a result, the current will decrease to half of its original value. This relationship is a fundamental concept in both direct current (DC) and alternating current (AC) circuits, although many students primarily visualize it in DC contexts.

Other statements in the options may suggest varying conditions or specific circuit types (AC or series), but the relationship holds true generally across all types of circuits as long as the voltage is constant. Understanding this concept is essential for interpreting both theoretical and practical situations in electrical engineering.