48) The power factor of a purely resistive circuit is

49) The r.m.s value of A.C is equal to

50) A circuit has an impedance of 22 ohms and drawing a current of 10 amperes at 0.8 power factor lagging. Which one of the following will be the apparent power?

51) When two wattmeters are used to measure power of a 3 phase balanced circuit and one wattmeter reads negative, it means the angle of lag is

52) The purpose of a backup fuse is to provide protection against