This is in the wrong category, but to answer it... you can't correct the device itself. The error arises from wear and tear. All you can do is calibrate against calipers or other references of known accuracy* and record the correction to be made to its readings.
*Accuracy - or precision. I can never quite remember the difference and which is the correct one of the two here.
The scale doesn't start at zero, so you need to compromise or you get a systematic error.
Zero error is defined as the condition where a measuring instrument registers a reading when there should not be any reading. In case of Vernier calipers it occurs when a zero on main scale does not coincide with a zero on Vernier scale. Source: calculatored and written by Shaun Murphy
Suppose say you have plastic rule new one. There you will be having zero marking. When you have to measure the length of a rod then you would keep zero marking at one end of the rod and the marking where the other extreme of the rod is taken to be length of the rod. say it is at 4 cm. So 4cm is the length. And suppose the ruler is an old one whose edge got damaged. Now you don't have zero marking so visible there. So you have keep the end of the rod at say 1 cm marking. Now the error that we commit is known as zero error. Here the error is positive. ie +1 cm. So as the other end of the rod is at 5cm marking then the correct length is got by applying zero correction. As zero error is +1 cm, then zero correction would be -1 cm So the correct length 5-1 ie 4 cm. Same way in case of vernier, if zero of vernier is at left side of zero of main scale, then the zero error is negative. If zero of vernier is right side of zero of main scale then error is +ve as we have seen in the earlier old ruler case. Same way in case of screw gauge as the head scale zero is above pitch line then error is negative and as head scale zero is below pitch line then zero error is positive.
If you are doing your job properly, you DO!
the correction which is made to get correct measurement after zero error
The zero error of vernier calliper is defined as :-The zero error is equal to the distance between the zero of the main scale and the zero of the vernier scale.
A zero error is a non-zero reading shown on a scale when the jaws of the vernier calipers are fully closed and nothing is being measured. We must align the zeros of the main and vernier scale together. If not able to do so,we should add or subtract according to whether it is a positive or negative error.
look for the zero marking in the main scale and focus your eyes to the mark below it.
if the zero of vernier scale lies on the right side of the zero of the main scale , then error is known as a positive error .
It is a defect in a measuring device (Vernier Callipers & Screw Gauge) & zero error is caused by an incorrect position of the zero point.
The zero error in the vernier calipers and micrometer screw gauge when the O mark on the main scale is not in line with the pointer.
The zero error of a measuring instrument is the measure that it shows when it should actually be showing zero.
The Vernier caliper is an extremely precise measuring instrument Error is almost impossible The error that we must always look out for is the zero error and parralex error.
The scale doesn't start at zero, so you need to compromise or you get a systematic error.
Zero error is defined as the condition where a measuring instrument registers a reading when there should not be any reading. In case of Vernier calipers it occurs when a zero on main scale does not coincide with a zero on Vernier scale. Source: calculatored and written by Shaun Murphy
It occurs when the '0' marking of the main scale is not in line with the '0' marking of the vernier scale when the jaws are fully closed.
Suppose say you have plastic rule new one. There you will be having zero marking. When you have to measure the length of a rod then you would keep zero marking at one end of the rod and the marking where the other extreme of the rod is taken to be length of the rod. say it is at 4 cm. So 4cm is the length. And suppose the ruler is an old one whose edge got damaged. Now you don't have zero marking so visible there. So you have keep the end of the rod at say 1 cm marking. Now the error that we commit is known as zero error. Here the error is positive. ie +1 cm. So as the other end of the rod is at 5cm marking then the correct length is got by applying zero correction. As zero error is +1 cm, then zero correction would be -1 cm So the correct length 5-1 ie 4 cm. Same way in case of vernier, if zero of vernier is at left side of zero of main scale, then the zero error is negative. If zero of vernier is right side of zero of main scale then error is +ve as we have seen in the earlier old ruler case. Same way in case of screw gauge as the head scale zero is above pitch line then error is negative and as head scale zero is below pitch line then zero error is positive.