This is best answer by B.E students during viva. >---------------------> This one is for those who had nightmares during their Engineering Viva's (EEEs and ECEs). They bring back fond memories for those who care to smile at the past..

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Interviewer: Why is a thicker conductor necessary to carry a current in A.C.as compared to D.C. ?

Candidate : An AC current goes up and down (drawing a sinusoid) and requires more space inside the wire, so the wire has to be thicker.



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External (to student) : "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!" ------------------- good one : - )



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Interviewer: How will you tell if that wall outlet carries AC or DC?

Candidate: I will put my finger in. If it is pushed away, it is AC. If it gets stuck, it was DC.



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Interviewer: H! ow will you reverse direction of an Induction motor?

Candidate: I will remove the four bolts at the x-ud, turn the motor around, and put back the bolts.



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Interviewer: How do you start a synchronous motor?

Candidate: Vrrrrrrrmmmmmmmmmmmmmmmmmmm (in rising pitch)

Interviewer: Stop! Stop!

Candidate: rrrrrrrmmmmmmmmmmmmmmmmmmmm (in falling pitch)



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Examiner: "What is a step-up transformer?"

Student: "A transformer that is put on top of electric poles."

Examiner (smiling): "And then what is a step-down transformer?"

Student (hesitantly):"Uh - A transformer that is put in the x-udment or in a pit?"

Examiner (pouncing): "Then what do you call a transformer that is installed on the ground?"

(Student knows he is caught-can't answer)

Examiner (impatiently): "Well?"

Student (triumphantly): "A stepless transformer, sir!"