Click the Exhibit button. In the exhibit, which power problem is illustrated?

Question

Options

• ADC offset
• BVoltage fluctuation
• CHarmonic distortion
• DFrequency variation

• A
  9% (5)
• B
  2% (1)
• C
  5% (3)
• D
  84% (47)

Explanation

Frequency variation occurs when the AC power supply deviates from its standard frequency (50 or 60 Hz), which in an exhibit would appear as a sine wave with cycles that are visibly compressed or stretched compared to a reference - meaning the waves are closer together or farther apart than normal, not distorted in shape or amplitude.

DC offset (A) is wrong because it would show the entire waveform shifted above or below the zero baseline, rather than a change in cycle timing. Voltage fluctuation (B) is wrong because it refers to changes in the height (amplitude) of the waveform, not the spacing between cycles. Harmonic distortion (C) is wrong because it would show a misshapen or clipped sine wave caused by unwanted frequency multiples, altering the wave's form rather than its timing.

Memory tip: Think of frequency variation as a change in the rhythm of the wave - the cycles speed up or slow down like a song playing at the wrong tempo, while the shape and height of the wave remain clean and unchanged.

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