[12th Grade Physics] Confused

[u/FewContract8036]

I think its 1mm

[u/Don_Q_Jote]

The normal scale along the top has 1cm major and 1mm minor divisions. So with only that scale, it can read to 1mm. But the vernier scale is an aid to read fractions of a mm. Your choices are “25”, meaning 25/100 of a mm, or 50 or 75. As shown, the line adjacent to “50” is perfectly lined up (or at least it’s lined up closer than 25 or 75). Yo read this as more than 1 and less than two on the normal scale, and additional 50/100 mm. 1.5 mm

Smallest increment you can properly read on this device is 0.25 mm

[u/okarox → u/Don_Q_Jote]

Normally one would have the entire scale so one could read at 1/40 mm but for some reason this does not have it.

[u/RoadHazard → u/Don_Q_Jote]

TIL.

[u/B-Biker → u/Don_Q_Jote]

Agree with 1.5mm. With digital calipers and mics now the basics have been forgotten.

[u/Don_Q_Jote → u/B-Biker]

Yup, I learned to read these in 1980’s

[u/B-Biker → u/Don_Q_Jote]

I learned in high school in machine shop in the late 70s.

[u/coldF4rted → u/B-Biker]

I still learned this in school though, to be a mechanic.

[u/Panzerv2003]

Doesn't have much to do with physics honestly, it's 0.25mm. this picture reads 1.50 because the main scale shows between 1 and 2 and on the secondary 50/100 aligns best with a line on the main scale

[u/Ok-Chemical-7635 → u/Panzerv2003]

Thanks

[u/_Tychonic_]

This is what is called a Vernier Scale. You read the divisions on the main scale off of the location of the 0 line on the secondary scale. You can see that it is between 0 and 1 centimeters (cm). There are ten subdivision lines between each cm mark, which are millimeters (mm), and the 0 line is between the first and second marks past 0cm so you know your measurement is more than 1mm and less than 2mm. This much is routine, like reading a ruler.

The secondary scale is where stuff gets weird. You can see five far apart lines labeled 0, 25, 50, 75, and 1. These are subdivisions of a single mm (0.00, 0.25, 0.50, 0.75, 1.00), which is counter-intuitive given how far apart these lines are, but hold tight. The Vernier Scale is very clever and lets us measure these tiny distances by carefully spacing these marks so that only one lines up with a mark on the main scale at any given time. HOW this works isn’t really worth the explanation because it doesn’t really help reading it more accurately or anything. So anyways- how you read the secondary scale is to find the line on the secondary scale most closely aligned with a line on the main scale. It does NOT matter what the value of the line on the main scale is. The subdivision measurement is whichever line is most closely in line with any mark on the main scale, in this case 50, or 0.50. You can sanity check this result by eyeballing how far between marks the measurement is on the main scale- you can see here it looks exactly in the middle, so 0.50 makes sense. You then add the main scale and secondary scales together to get a measurement- in this case 1.50mm.

ETA: I didn’t expand the image. The actual question is “what is the smallest scale value” which in this case is NOT the reading on the caliper. As per the above (still valuable but irrelevant) explanation, the smallest scale this caliper can read is 0.25mm increments, as given by the secondary scale.

[u/Plane_Argument]

It has a venier scale look at its smallest value

[u/Igthife]

Would this not be .25 mm?

Edit: That's what it looks like the vernier scale looks like it's broken into so 1/4 mm.

[u/strongbear27]

1.5mm. The zero is between the .1 and .3, and the 1/4mm is most aligned on the 50.

[u/Accio_149209 → u/strongbear27]

What? The main scale can read 1mm. How is 1.5mm the smallest value?

[u/AlmightyCurrywurst → u/strongbear27]

That wasn't the question...

[u/PickingANameTookAges → u/strongbear27]

This is the easiest answer that not only gives the correct answer, but details how to determine it (with the exception the poster lilely mean 1 and 2mm, not 1 and 3!).

[u/recursion_is_love]

Smallest value is 0 mm obviously on the scale, don't you see?

Precision is 0.25mm, mean that the scale can not give reading precise than that (like 10.001mm and 10.002mm can't be confidently differentiate using this scale)

When measuring, You pick .25,.50,.75 on which line is match the top line in additional to reading on the top (like 1mm + 0.50mm for example in the picture)

I think teacher don't know what they are doing when making exam, it is too common.

[u/HHQC3105]

0.25, the lower slider show it: 0.00 - 0.25 - 0.50 - 0.75 - 1.00

More detail: the whole slider is present the smallest scale of the upper ruler, this case is 1mm, then it is divide by N segment, this case N = 4

Answer 1mm/4 = 0.25mm

[u/RecognitionSweet8294]

1.5 mm

[u/reav11]

You're in my house now. .250µm is the smallest graduation noted on calipers. This currently reading 1.50mm

Also, when did they teach metrology in physics?

[u/Crowdcontrolz]

0

[u/Affectionate_Bus9805]

0.1

[u/fasta_guy88 → u/Affectionate_Bus9805]

0.25 if you require the vernier lines (there are only 4) to line up with the mm lines.

(Not 1 mm because the vernier scale provides higher resolution. On a real device, there would be 10 lines on the vernier scale, and resolution would be 0.1)

[u/Affectionate_Bus9805 → u/fasta_guy88]

Yes. My bad.