We might call this a descriptive use of the progressive. Telic verbs like joke or explain or lie ordinarily express something done-to-the-end which brings about a change of state: a joke excites laughter, an explanation brings about understanding, a lie brings about a misunderstanding or false belief. When such a verb is cast in the progressive it sometimes implies imperfectivity, an action&mdash;joking, explaining, lying&mdash;in progress but not yet completed; at other times however it is used to describe an action, to characterize it as possessing the quality of a joke, an explanation, a lie.  


  If he says that, he&rsquo;s lying.
  He wasn&rsquo;t ordering you to do it that way, he was explaining why it should be done that way.
  He wasn&rsquo;t serious, he was just joking.  


The same recategorization may be observed with some atelic verbs. BE, for instance, is ordinarily a stative, but if cast in the progressive it describes behavior rather than asserting existence. 


  John isn&rsquo;t really a jerk, but he&rsquo;s certainly being one tonight.


Note that in my &lsquo;serious&rsquo; and &lsquo;jerk&rsquo; examples the progressive construction is contrasted with a stative copular construction, not with a perfective construction.

My guess&mdash;it&rsquo;s no more than that, and if anyone has a better understanding of this I&rsquo;d be glad to hear of it&mdash;is that this use is a matter not of the Viewpoint Aspect, imperfectivity, conferred by the progressive construction, but of its Lexical Aspect: stativity. That is, the progressive is employed because it attributes a state, a quality, to the subject rather than an action.

Can progressive aspects express the ongoing effect of an activity?
According to Ohm's law, V=IR (voltage equals current times resistance).

So if the voltage increases, then the current increases provided that the resistance remains constant.

I know that Voltage or potential difference means work done per unit positive charge in bringing that charge from one point to another.

So according to Ohm's law, if the work done per unit charge increases then current will increase. How can this be true? Point out my mistakes.
