What is NPTEL?Will they help in clearing our doubts while studying btech??Is it free??

NPTEL is a national programme to help out engineering students across India. These are the tutorials in video and material form. These help to understand the concepts in deeper level. You can use it as many times you need. They don't clear doubts rather help you clear the concepts apart from your class learnings.

Yes, It is free. You can take any course you want to learn. To get certified at a national level you have to take exam only and complete the assignments with some exam registration fees. Except that NPTEL is free of cost.

Hope it Helped!