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 transformer 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?

Interviewer (impatiently): Well?

Student (triumphantly): A stepless transformer, sir!