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Difficulty: HardDirect Current (DC) vs. Alternating Current (AC)

An off-grid weather monitoring station stores electrical energy in a 24 V24\text{ V} direct current (DC) battery bank but must operate a 120 V120\text{ V} alternating current (AC) transmitter. Which component is required to power the transmitter from the battery bank, and how does it manipulate the electrical current?

  1. A
    A rectifier, which converts continuous unidirectional current into an oscillating bidirectional waveform
  2. B
    A step-up transformer, which increases steady direct current voltage by maintaining a static magnetic field
  3. An inverter, which converts unidirectional direct current into alternating current that periodically reverses polarityAnswer
  4. D
    A forward-biased diode bridge, which switches electron flow from conventional positive flow to negative flow

Answer

An inverter, which converts unidirectional direct current into alternating current that periodically reverses polarity
Batteries store and supply direct current (DC), in which electrons flow in only one direction with constant polarity. An inverter uses electronic switching circuitry (such as transistors or MOSFETs) to transform this unidirectional current into alternating current (AC), where the voltage and electron flow periodically alternate and reverse direction to match the requirements of AC equipment.

Step-by-Step Solution

1
Identify the power source and the load power requirements
The energy source is a 24 V24\text{ V} battery bank providing steady direct current (DC), while the load requires 120 V120\text{ V} alternating current (AC).
Determining the input waveform (unidirectional DC) and output waveform (alternating bidirectional AC) establishes the necessary power conversion process.
2
Evaluate the function of conversion and transformation devices
Transformers require alternating current to induce voltage and cannot operate on steady DC; rectifiers convert AC to DC; inverters convert DC to AC.
An inverter electronically switches and modulates DC to generate an alternating voltage and current waveform that periodically reverses direction.
3
Select the component that performs DC-to-AC conversion
An inverter changes the unidirectional DC into the required AC waveform.
The transmitter requires an AC waveform with reversing polarity, which only an inverter can synthesize from a DC storage bank.

Key Concept

Direct Current (DC) flows continuously in a single direction, whereas Alternating Current (AC) periodically reverses direction and polarity. Converting DC to AC requires an inverter, whereas converting AC to DC requires a rectifier.
Estimated Time:45s
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Topics

Direct Current (DC) vs. Alternating Current (AC)

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