# Uncertainty in the measurement tools

There is a question which states, find the percentage uncertainty when the measured value of an object is $$6\text{cm}$$, given that a vernier caliper is used.

$$60.0\text{mm} \pm 0.1\text{mm}$$

Hence we have: $$\frac{0.1}{60.0}\times 100\%=0.167\%$$

However, isn't absolute uncertainty of the instrument, the lowest division divided by $$2?$$ So if our instrument is the vernier caliper, the lowest division is $$0.1\text{mm}$$. Therefore, the absolute uncertainty will be then $$0.05\text{mm}$$, which gives our uncertainty calculation to be:

$$\frac{0.05}{60.0}\times 100\%=0.083\%$$

Furthermore in the markscheme it says:

$$\frac{0.1}{6}\times 100\%=1.67\%$$

At the moment I am so confused to which one is the true answer to this question, could anyone help me understand this?

• 0.083% looks good to me. – PM 2Ring May 1 at 16:32
• Ok thank you, so is the mark scheme wrong? – Aurora Borealis May 2 at 18:36
• Yes, I believe it's wrong, and you are right. – PM 2Ring May 2 at 18:48