What does it mean variable Direct Current ?

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Variable Direct Current (DC) refers to a DC voltage that can change over time, unlike a constant DC source. This variability can lead to measurements of different voltages and currents at different points, similar to how Alternating Current (AC) behaves. The discussion highlights the confusion between variable DC and traditional AC, emphasizing that while the voltage may change, the source remains classified as DC. The key point is that variable DC involves adjusting the voltage level rather than the current direction. Understanding this concept is crucial for applications that require precise voltage control.
vkash
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what does it mean "variable Direct Current"?

I am confused on the point where i see the word variable DC in a question(see attachment). If a DC vary like a curve then in some cases it can be like AC.
How is it varying
(Don't tell me answers.)
 

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vkash said:
I am confused on the point where i see the word variable DC in a question(see attachment). If a DC vary like a curve then in some cases it can be like AC.
How is it varying
(Don't tell me answers.)
attachment.php?attachmentid=44417&d=1330285199.png

The DC voltage source is not varying , it's variable .

You apply a DC voltage at some value, and measure V1, V2 and I.

Then, change the DC voltage to a different value, and measure V1, V2 and I.

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