Significant Figures and Conversion of Physical Quantities

Every one of the experimental measurements has some type of uncertainty related to them. To guarantee accuracy and precision in estimations and get genuine information, a proper technique to make up for these uncertainties was required and this resulted in the significant figures. Here, we will discuss what are significant figures, significant figures rules, and their real-life application. In the later section, we talk about the basic units of measurements or fundamental physical quantities.  

What are Significant Figures?

When reporting analytical concentrations, having an appropriate amount of significant data is critical for having a meaningful level of power resolution. To calculate how many significant figures are required, a variety of methods or characteristics can be employed. Three important figures are usually sufficient.

The number of significant single digits (0 to 9 included) in the coefficient of expression in scientific notation is referred to as significant figures. The number of significant figures in an expression reflects an engineer’s or scientist’s level of confidence or precision in expressing a quantity.

Significant Figures Rules

When measuring the significant figures of a given measurement, certain requirements must be followed. The three most important significant figure rules are:

Rule 1 – All the non-zero digits are considered significant.

This is one of the more self-evident rules. When you use a device like a ruler or a thermometer to try to measure something and it gives you a number, you’ve made a measurement decision. Only that single-digit will have meaning in the overall number you acquire as a result of this measurement process.

Rule 2 – Zeroes which are placed between non-zero digits are significant.

This is another rule whose title is self-explanatory. Zeroes are not significant according to the significant digit rule one. However, the second rule indicates that any zero between two significant numbers becomes a significant number as well.

Rule 3 – A final zero in the decimal portion is significant, whereas leading zero is not.

The trailing zeroes are only used as a placeholder for other numbers, and they are mainly used as significant numbers. Any amount of zeros trailing in front of a number is not regarded as a significant digit and is therefore non-significant.

Some Other Significant Figures Rules:

1. A significant figure is one having the following zero among a whole number and the decimal display. Placing decimals is uncommon, however in this case, “450.” indicates that the zero after four and five is to be considered a significant digit. As a result, there are three significant numbers present here.
2. A trailing zero in a whole number that isn’t followed by a decimal is also not termed a significant digit.
3. There are an infinite number of significant digits in exact numbers. It may appear perplexing, but this rule only applies to specific numbers that appear as definitions.
4. Important figures are numbers that appear in scientific notation, such as N x 11x, while “10” and “x” are not to be termed significant figures.

Significant Figures Examples

Following are some examples of significant figures: 

• 5409 – here there are 4 significant figures
• 80.08 -here there are 4 significant figures
• 5.00 – here there are 3 significant figures
• 0.00900 – here there are 3 significant figures

Let’s take a closer look at how the concept of significant figures is used in real-world situations.

1. Precision

Precision refers to how near two or more quantities are to each other. When repeated, the level of measurement yields the same result.

2. Accuracy

It is the measuring level that gives accurate and consistent results (this means there are no systematic or random errors). The observed outcomes are consistent with the true outcomes.

The following are some of the factors that can lead to measurement uncertainty:

• If the device which is being used for measuring has limitations
• The irregularity of the object is being measured
• The ability and expertise of the individual tasked with measuring
• A large number of factors can obstruct measurement since they are highly influenced and dependent on the context

Conversion of Physical Quantities

Measurement is a technique used to determine an object’s qualities by comparing it to a standard. Physical quantities are those aspects of a material or system that can be measured and quantified. They can be expressed as the combination of a number (n) and a unit (u).

Fundamental quantities can be divided into two types. These are fundamental and derived quantities.  Fundamental physical quantities are the quantities that are easily measured. The derived physical quantities are those that cannot be measured practically but can be calculated mathematically.

What are fundamental physical quantities?

The seven fundamental physical quantities that are measured in base or physical fundamental units in physics are mass, length, time, electric current, amount or quantity of substance,  temperature, and luminous intensity. The other kinds of physical values are described mathematically by combining these seven base units.

The different types of physical quantities are:

1. Length
2. Mass
3. Time
4. Electric current
5. Temperature
6. Quantity of substance
7. Luminous Intensity
8. Plane angle
9. Solid angle

There are seven fundamental physical quantities. The latter two units, Plane angle and Solid angle are SI subsidiary units that are dimensionless. The subsidiary units are used to distinguish between a really dimensionless quantity and an angle, which are two separate measurements.

It’s worth noting that the current can also be calculated if the number of charges flowing in the conductor is known. However, measuring current with equipment like an ammeter is easier than counting the number of charges flowing in the circuit. As a result, current is seen as a fundamental physical quantity, while charge is regarded as a derived quantity.

Physical Quantity	Unit	Symbol
Length	Meter	m
Mass	Kilogram	kg
Time	Second	s
Electric Current	Ampere	A
Temperature	Kelvin	k
Quantity of Substance	Mole	mol
Luminous Intensity	Candela	cd

In sum, you have learned about the significant figures, their rules, and the seven fundamental physical quantities. Significant figures are the digits that are considered necessary for determining the value of something. Find out more about other class 11 concepts such as classification of elements & periodicity in properties, states of matter, and equilibrium on the Unacademy website.