ECE interview

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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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: How will you reverse direction of an
induction motor?
Candidate: I will remove the four bolts at the base,
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)
--------------
Interviewer: How do you limit surge current within an
integrated
circuit?
Candidate: By using a miniature circuit breaker.
--------------
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!"
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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 transfomer that is put in
the
basement 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!"_________________________