Logical Puzzles

This was little bit annoying... One of my friends attended an interview.  He was able to get through his aptitude and technical rounds.  But finally they made him to sit before HR and he asked logical questions..    Hey u know he was knocked out due to that.... So I never let this to happen in your story... So lets learn how to solve some logical puzzle...

They asked....

1.  3 bulbs are in 1st floor  and 3 switches are there in ground floor.. U can go up only once and operate the switches.  U need to come down and identify the corresponding switch to those bulbs.  You need not use any other devices.  

Solution:

First turn on a bulb and leave for few mins.  Then switch off it and turn on the other and go upstairs.  The bulb glowing corresponds to the switch that is on.  Touch the rest two.   The one which is warm is the one you switch on first.  So thats the solution.

we can find more puzzles online.....

They ask relationship problems... Like..

A man is holding photo of a man and tell "I don't have sisters and brothers but this man's father is my fathers son".  Who is this man in the photo...????

Solution: 

"The man in the photo is his son:

This man's father is the man in the photo's father, i.e "is my father's son".  The man in the photograph is the son of someone who "is my father's son".  The man holding the photograph has no siblings.  His father's son is himself.  He is the father of the man in the photo.   So the man in the photo is his son.