24) The ratio of RMS value to the average value of an alternating current waveform is called

25) Age of a father is 3 more than 3 times his son's age. Five years before age of father was one less than 5 times his son's age. Age of father is

26) Pyrometry deals with the measurement of

27) Endurance limit is associated with

28) Which of the following materials generally exhibits a yield point?