Sparks !!

Bunny and bunny designer was talking to DS. He explained the switch and called it a relay. DS had an obvious question whats the Relay ? ... Bunny of course had answer ready that its the switch. Though DS remembered that relay was a sort of 220 volts switch but switch can be of any voltage. Bunny agreed. The diagram was following :

DS, asked if the lever on bunny's switch is small or big ! Bunny said its big. Good Size does matter, replied DS.  Bunny complemented it further that bigger it is cleaner it is.

Asked DS, after the use as well ? ... Yes, replied Bunny. DS: Hmm ... are you sure of the Carbon deposits on big lever after the use ? .... Why would that be ? asked Bunny.  DS: wouldn't a voltage difference cause the sparks when your big lever meets the pit ? Bunny : Why would there be spark ?

DS: There is always the spark!
Bunny: I don't know ... but why ?
DS: Because there is a potential difference here ... so when big lever meets the pit ... there is a spark!!
Bunny: Oh ya ... you're right ..
DS: So you sure now that after the use the big lever will not be clean .. it will be dirty ?

Bunny : Yes, I understood this well ...
DS : What did you understand ?

Bunny : That with the spark, there will be carbon deposit and hence the lever will be dirty.
DS: You didn't understand a thing ;)

Everyone around burst out in laughter, DS din't know that if that was because they understood the joke or realized that there was one !!!