Question

The resolution of an indicating instrument can be defined as:

1) Variation in the meter reading for the same applied input.

2) Detectable change in the deflection due to the smallest change in the applied input.

3) Detectable change in the output due to drifting of the pointer.

Which of the above statements are correct?

1. 1 only
2. 2 only
3. 3 only
4. 1 and 3

Answer 1

Correct Answer - Option 2 : 2 only

• Resolution is the ability of the instrument or measurement system to detect and faithfully indicate the small changes in the characteristics of the measurement result.
• Let’s assume the resolution is denoted by ‘δ’
• A small δ implies good resolution and a large δ implies poor resolution.

 

Note: The number of digits displayed doesn’t indicate the resolution of the instrument.

Non-electrical Example:

Consider two rulers. One marked in 1/16 inch and another marked ¼ inch. 1/16 inch marked segments offer greater resolution than one marked in quarter-inch segments.

Electrical Example:

A maximum resolution of 100 mV (0.1 V) means that when the multimeter’s range is set to measure the highest possible voltage, the voltage will be displayed to the nearest tenth of a volt.

Resolution is improved by reducing the DMM’s range setting as long as the measurement is within the set range.