Physics: Mass & Volume Lab 1 Sample Report

very accurately made and must be read to a fraction of

its smallest scale division.

2

Movable

Jaw

Stem

Fixed

Jaw

Vernier

Scale

When an instrument is used to the limit of its precision, certain errors occur that

cannot be eliminated. These errors are called random errors. When you make a series of

measurements of a physical quantity, the individual results usually differ among

themselves because of the random errors involved. The best value of the quantity

measured is then the average of the values obtained.

The precision of measurements can usually be increased by using more accurate

and complex equipment and by being careful to eliminate errors as much as possible. No

matter what type of instrument you are using, you should always try to make

measurements with the greatest accuracy attainable.

The Vernier Caliper

When you make a measurement using a meter stick you have to estimate the

tenths of a millimeter (the millimeter being the smallest division on the meter stick). A

vernier is a device that helps you to read the fractional part of a scale division. It is a

small auxiliary scale that slides along the main scale. The scale of the vernier is different

from those of the main scale, but they are simply related.

The vernier caliper (see figure above) consists of a fixed part and a movable jaw.

The fixed part includes a stem, on which is the main scale (in centimeters and

millimeters) and a fixed jaw attached to the stem. The movable jaw is free to slide on the

fixed scale and has a vernier scale engraved on it. The vernier is divided so that ten

divisions on it cover the same interval as nine divisions on the main scale. Hence, the

length of each vernier division is 9

10 the length of a main-scale division. When the jaws

are closed, the first line at the left end of the vernier called the zero line coincides with

the zero line on the main scale. However, the first vernier division is 0.1 mm away from

the first main scale...