What kind of job opportunities are there for ethical hackers does there pay differs from normal programmers and what are best institutes to pursue it?

Today there are more opportunities than ever before for people who do " white hat attacks". Just Google Whitehat attack and you'll find agencies that do this. My advice would be to get as much education as you can in the IT area and then pursue a career with one of these organizations when you graduate.

This field is called "information security" or "infosec."

"Hacking", meaning defeating information security, is a term from the popular media. Inside the profession, we call it "cracking." We call the people who do it maliciously "cybercriminals".

There are tremendous opportunities in this area. The so-called "internet of things" promises to break this field wide open. When cybercriminals start hijacking thermostats and cars, things might get really challenging.

To get into this field you'll need to learn about cryptography and certificate management. It requires an excellent understanding of information technology as a starting point. Focus your university education on IT.

You can read about this field; I recommend three online newsletters, by Brian Krebs, Bruce Schneier, and Troy Hunt. Mr. Krebs as a great book out called "Spam Nation." Dr. Schneier has published several books, from mathematical texts on cryptography to popular books on the sociology of trust.

A big part of infosec is securing web sites on the public internet. http://owasp.org/ has lots of good material on that topic.

If you get really good at this AND you stay on the right side of the law, you can have a very interesting and lucrative career. Possible employers include big company IT departments, IT product developers, infosec consultancies, anti-virus companies, and even a police force.

Be careful. It's easy to stumble onto the wrong side of the law in this field. Lots of institutions and police forces don't even begin to understand the difference between a white-hat intruder and a black hat (criminal) intruder. Nobody has a sense of humor about this any more. If you discover a vulnerability in your university's IT system and tell them about it, they may react by expelling you and prosecuting you rather than saying "thanks."