If you have lost your original aadhar card than you can use the e aadhar by taking the print out of it.

But some centres for jee exams do not allow anything except the admit card  for the exam .

Check your admit card if there are any instructions given for the aadhar card or not.

Even if it is not given in admit card it is good to take aadhar with you . If not allowed you can give it temporarily to the invigilator.

All the best