Interviewer: Why is a thicker conductor necessary to carry a current in A.C. as compared to D.C. ?
Student: An AC current goes up and down (drawing a sinusoid) and requires more space inside the wire, so the wire has to be thicker.
Interviewer: How will you tell if that wall outlet carries AC or DC?
Student: I will put my finger in. If it is pushed away, it is DC. If it gets stuck, it was AC.
Interviewer: How will you reverse direction of an induction motor?
Student: I will remove the four bolts at the base, turn the motor around, and put back the bolts.
Interviewer: How do you start a synchronous motor?
Student: Vrrrrrrrmmmmmmmmmmmmmmmmmmm (in rising pitch)
Interviewer: Stop! Stop!
Student: rrrrrrrmmmmmmmmmmmmmmmmmmmm (in falling pitch)
Interviewer: How do you limit surge current within an integrated circuit?
Student: By using a miniature circuit breaker.
Interviewer: ” Why does a capacitor block DC but allow AC to pass through?
Student: See, a capacitor is like this —~~ ~~— , OK. DC Comes straight, like this ———-, and the capacitor stops it. But AC,goes UP, DOWN, Up DOWN and jumps right over the capacitor!”
Interviewer : “What is a step-up transformer?”
Student : “A transformer that is put on top of electric poles.”
Interviewer (smiling): “And then what is a step-down transformer?”
Student (hesitantly): “Uh – A transfomer that is put in the basement or in a pit?”
Interviewer (pouncing): “Then what do you call a transformer that is installed on the ground?” (student knows he is caught — can’t answer)
Interviewer (impatiently): “Well?”
Student (triumphantly): “A stepless transformer, sir!”.