✅ The correct answer is option D.
It is a method of controlling the speed of an AC induction motor, whereby speed, current and torque can all be accurately controlled.
✅ The correct answer is option C.
Theodore Maiman built the first working laser using a ruby rod while working at Hughes Research Laboratories in Malibu, California. It lased for the first time on May 16, 1960.
✅ The correct answer is option C.
1983 Fred Cohen, while working on his dissertation, formally defines a computer virus as ‘a computer program that can affect other computer programs by modifying them in such a way as to include a (possibly evolved)copy of itself.’