Digital joulemeter wattmeter rvfm 211 001 the edu lab joulemeter wattmeter is light compact and designed for class demonstration or student use the unit can measure energy taken up by a load either by ac power or dc power from 1j to 999 999j 1mj to 999 999mj and can also measure power level of 200mw to 200w one pair of 4mm sockets is also provided to indicate the instantaneous power depending on mw mj or w j range 1v full scale deflection represents 100mw or 100w respecti