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You have to find the direction of rotating magnetic plate ....
Microsoft Interview Questions and Answers
(Continued from previous question...)
85. You have to find the direction of rotating magnetic plate ....
Question:
You have to find the direction of rotating magnetic plate by using minimum sensors on plate, each sensor return a timestamp whenever the Head of the plate passes through it,
maybe an answer:
2 sensors is the correct.
place it at an angle of 90 to each other.
Lets consider the arrangement as
S1
X.......S2
X
we need 3 timestamp from these sensors.
2 from S1 call it (tS11, tS12) and 1 timestamp from S2 (tS21)
if(ts11 - ts21) > (ts21 - ts12)
rotating in anti clocwise direction
else
Clockwise.
maybe an answer2:
thats the solution I had in mind. The angel of 90 degrees is not that important. All we need to know is that the 2 sensors are not at 180 degrees and in which 2 quadrant they are located in.
Also we need to have the assumption that the plate is rotating at a constant speed else this solution wont work.
In case of variable rotation speed we would need 3 sensors. Put them on say at 1 O' Clock, 2 O'Clock and 3 O'Clock. Take 3 time stamps. from 3 sensors.
If sensor 1Time stamp is > sensor 2 Time Stamp> sensor 3 Time stamp the plate is moving counter clock wise else clock wise.
(Continued on next question...)
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