28. The fundamental frequency of an organ pipe open at one end is 300 Hz. The frequency of 3rd overtone of n Find n.xthis organ pipe is 100 Hz. 29. A carnot engine works between temperatures 327C and 27C. If the engine takes 1600 J of heat from the higher temperature reservoir, the work done by the engine per cycle (in Joule) is equal to Consider a p-n junction diode which has a potential drop of 0.5 V which is to be taken independent of current (under forward bias). If we want to use 1.5 V cell to forward bias the diode then what should be the value of resister (in 2) used in series with the diode so that current may not exceed 10 mA, and hence may work safely.