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

A technician needs to operate a 120 V120\text{ V} alternating current (AC) power tool using a 12 V12\text{ V} direct current (DC) vehicle battery as the power source. Which sequence of components is required to operate this equipment?

  1. A
    A step-up transformer connected directly to the battery, followed by a rectifier to alternate polarity
  2. An inverter to convert the DC supply into AC, combined with a transformer to increase the voltageAnswer
  3. C
    A rectifier bridge to produce an alternating waveform, followed by a series diode to prevent reverse flow
  4. D
    A voltage divider to convert DC voltage into current flow before boosting frequency with an inductor

Answer

An inverter to convert the DC supply into AC, combined with a transformer to increase the voltage
A battery supplies unidirectional direct current (DC). Because standard transformers require alternating current (AC) to induce voltage across their windings, the DC must first be converted into AC using an inverter circuit, which can then be stepped up to the required 120 V120\text{ V} AC level.

Step-by-Step Solution

1
Identify the power characteristics of the source and the load
The source provides 12 V12\text{ V} steady direct current (DC), whereas the load requires 120 V120\text{ V} alternating current (AC).
Direct current flows continuously in one direction at constant polarity, while alternating current periodically reverses direction.
2
Determine the required electrical conversion and voltage transformation
DC must be converted to AC via an electronic inverter circuit, and the voltage magnitude must be increased tenfold.
Transformers operate on mutual induction created by varying magnetic fields, meaning voltage can only be stepped up or down efficiently after conversion to AC.

Key Concept

Direct Current (DC) maintains unidirectional flow while Alternating Current (AC) reverses direction periodically; conversion from DC to AC requires an inverter.
Estimated Time:45s
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Topics

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

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