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A voltmeter has a uniform scale with 150 divisions; the full-scale reading is 150 V and 1/5 of a scale division can be estimated with a fair degree of certainty. Determine the resolution of the instrument in volt.
0.2 V
0.1 V
0.5 V
1.0 V
0.2 V
The resolution of an analog measuring instrument is the smallest change in the measured quantity that can be detected reliably on the scale. For this voltmeter, it is determined by multiplying the voltage value of a single scale division by the fraction of the division that can be estimated.
The resolution of an analog measuring instrument is the smallest change in the measured quantity that can be detected reliably on the scale. For this voltmeter, it is determined by multiplying the voltage value of a single scale division by the fraction of the division that can be estimated.
Think of a clock face or a ruler where, even though the smallest printed marking is 1 unit, you can visually estimate halfway or a fifth of the space between markings to get a more precise reading.
Resolution=(Number┬аof┬аDivisionsFull-Scale┬аReadingтАЛ)├ЧFraction┬аEstimated тАФ determines the finest resolvable increment
Resolution=1┬аV├Ч51тАЛ=0.2┬аV тАФ specific calculation for this instrument
First, find the voltage value of a single scale division by dividing the full-scale reading by the total number of divisions: 150150┬аVтАЛ=1┬аV. Next, multiply this value by the fraction of the division that can be reliably estimated (51тАЛ), giving 51тАЛ├Ч1┬аV=0.2┬аV.
Resolution is finer than the basic least count when human interpolation or estimation is possible.
A full-scale reading of 150 V divided across 150 divisions yields 1 V per division.
Estimating 1/5 of a division enhances the effective resolution to 0.2 V.
Allows greater measurement precision than what is strictly indicated by the physical scale markers.
Subjective visual interpolation can introduce human parallax or estimation error.
Analog panel meters
Laboratory voltmeters and ammeters
Dial-based scientific instruments
Value per division = 150┬аV/150=1┬аV.
Resolution calculation = 1┬аV/5=0.2┬аV.
Option A is correct because it correctly accounts for the 1/5th fractional estimation.
A is correct тАФ The resolution of the voltmeter is 0.2 V, calculated by multiplying the value of a single division by the estimable fraction.
Always verify whether an instrument problem specifies an estimation fraction; if none is given, resolution defaults to the least count (value of 1 division).