Engineering Interview

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!".