Question:medium

DC current can be controlled by which of the following?

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Remember that capacitors and inductors only oppose changing current, not steady DC current.
Updated On: Jul 16, 2026
  • Impedance
  • Resistance
  • Capacitance
  • Inductance
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The Correct Option is B

Solution and Explanation

Think of this the way an electronics lab technician thinks about it, using a simple circuit picture.

  1. Take a battery connected to a resistor, this is a basic DC circuit. If you use a rheostat, a variable resistor, and slide it to increase resistance, the current drops immediately following \(I = V/R\). This is a direct, practical way to control DC current, and it is used in real circuits like fan speed regulators.
  2. Now replace the resistor with a capacitor. Current flows only briefly while the capacitor charges, then stops completely. You cannot maintain or adjust a steady current this way, so capacitance fails as a DC current controller.
  3. Replace it with an inductor. Right after switching on, the inductor resists the sudden rise in current, but after some time the current settles to a steady value set only by the wire's own small resistance. The inductor's opposition fades away for steady DC, so it is not a real controller either.
  4. Impedance combines resistance with reactance from capacitors and inductors, but since reactance needs a changing current to exist, impedance has little meaning in a pure, steady DC circuit.

Only resistance stays effective at all times in a DC circuit, so resistance is the right choice.

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