How to calculate percentage error of measurements from a voltmeter?

The question is: A voltmeter who's accuracy is guaranteed to within 2% of its full-scale reading is used on its 0-50V scale. The voltage measured by the meter is 15 and 42V. Calculate the possible percentage error of both readings.



I'm not sure if that means + - 2% of 15 and 42, or what % is 15 and 42 of 50?How to calculate percentage error of measurements from a voltmeter?
卤2% of full scale is 卤2% or 50 volts or 卤1 volt



so 1 volt is what percentage of 15 volts? 1/15 = 0.067 or 6.7% of reading.

the other is similar.



.How to calculate percentage error of measurements from a voltmeter?
If you have a voltmeter that measures +/- 2% at full scale and tie the leads together, it should read 0 volts exactly. So, at the left side of the scale it will be right on. This means that at mid scale (25 volts) it should be accurate to +/- 1%. And, so at whatever voltage you measure it should be accurate to (Vm/Vfull scale) x 2%.



At 15 volts it would be: (15/50) x 2% or +/- 0.6%.



At 42 volts it would be: (42/50) x 2% or +/- 1.68%



Hope that helps.