Units and Measurement

Edited By Team Careers360 | Updated on May 06, 2022 09:19 AM IST

Introduction:
Natural laws are explained in a unique way in Physics. This explanation includes a quantitative description, comparison, and measurement of various physical quantities. We must first create a standard unit of measurement before we can measure or compare a physical quantity. The weight of a lion is more than that of a goat. However, how many times have you done that before? Prashant towers over Robin, but by how much? To answer such questions, we'll need to build a unit. We can calculate that the lion's weight is 200 times that of a goat if the mass is the unit. If we take the length as a unit, we can easily conclude that Robin is 2 times the unit taller than Prashant.

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We need a universally acquired standard called a Unit to measure any quantity or compare two quantities. Any physical quantity is measured using a number and a specific unit.

Quantity X Unit = Measurement

List of topics according to NCERT and JEE Main/NEET syllabus:

unit of measurement Subtopics:

Units that are fundamental and derived
Instruments with the highest accuracy, precision, and the lowest count
Measurement errors
Figures of importance
Physical quantities' dimensions
SI Units
Absolute Errors
Significant Figures
Dimensional Analysis

Approximately 4% of questions come from the topic in JEE Mains and NEET.

Related Topics,

Important concepts and Laws:

Physics-scope and excitement;
Nature of physical laws;
Physics,
technology and society. (To be discussed as a part of Introduction and integrated with other topics)
Need for measurement:
Units of measurement;
Systems of units;
SI units,
Fundamental and derived units.
Length, mass and time measurements
Accuracy and precision of measuring instruments;
Errors in measurement;
Significant figures.
Dimensions of physical quantities
Dimensional analysis and its applications
Some important formulas of conversions are also written below
converting lengths,
1 millimeter to cm :- 1cm = 10mm
inches to metric :- 1 inch = 25.4 mm , 1 mm = 0.0393700787 in
1 inch in centimeters / centimeters to inches :- 1 inch = 2.54 centimeters.
1 acre in bigha:- One acre = 1.62 bigha
sq metres to sq ft :- 1 square meter = 10.764 feet
1 bigha in square feet :- 1 bigha = 27,000 square feet.
bigha to acre :- 1 Bigha= 0.6198347 Acre.
1 bigha in gaj :- 1 Bigha = 1,954.766117441 Gaj
sq metres to acres :- 4046.8564224 square meters = 1 acre
1 litre in millilitres :- 1 litre = 1000 ml,
metric ton to kg / 1 metric tonnes to kg :- 1000 kilograms = 1 metric tons
kilowatt-hour is the unit of electricity consumption which is also called as 1 unit of electricity

NCERT Notes Subject Wise Link:

Importance of Units and Measurement class 11:

The topic is crucial to understand since there will be no uniformity in measurement without a standard unit system. The only way to verify the correctness of any hypothesis is to use measurements. As a result, understanding Units and Measurements is critical because it deals with a comparison tool. Though it is a part of the school curriculum, namely the Physics syllabus for class 11, it is used in our daily lives. A review of the subjects covered in the following class XI Physics chapter will give you an idea of what to expect.

NCERT Solutions Subject wise link:

NCERT Exemplar Solutions Subject wise link:

Frequently Asked Questions (FAQs)

1. What is Units and Measurement?

The first step in understanding units and measurements is to know what these phrases mean. Measurement is the process of comparing any physical quantity to a numerical value. It establishes a benchmark for all aspects of life. Units, on the other hand, is the standard by which amounts of similar type are measured. The measurements are taken in accordance with internationally recognised units.

2. Conservation Laws in Physics?

SI Base Unit Definitions and In Units and Measurements

Let's go over the definitions of the various S.I units now that you've grasped the fundamental ideas of units and measures.

Metre - The length of the path taken by light in a vacuum in a second is measured as 1 metre.

Second - It is the SI unit of time established in terms of the frequency of radiation at which caesium atoms change states. It's written in s.

Candela - It is the unit of luminous intensity and is defined as the magnitude of the electromagnetic field.

Ampere - The ampere is the SI unit of electric current and represents one coulomb of electricity flowing every second.

Kilogram - It is the SI unit of mass and is the quantitative measure of inertia and is expressed as kg.m2.s-1

Kelvin - It is defined as 1/273.16 (3.6609 x 10 -3) thermodynamic temperature of the triple point of water.

Mole - It is defined as 6.02214076 × 1023 of a substance.

3. What Are Derived Units?

It's a SI unit of measurement made out of two or more of the seven basic units. In physics, there are numerous derived units. Area, volume, speed, force, surface tension, pressure, latent heat, and so on are examples.

4. What are the different types of errors which occur while measuring?

1. Constant errors

2. Systematic errors

3. Random errors

4. Absolute errors

5. Relative errors

6. Percentage errors

5. What are the conversions of? A). 4 inch in centimetre = ? B). 8 inch in centimetre = ?

4 inch in centimetre = 4 in * 2.54 cm = 10.16 cm

B). 8 inch in centimetre = 8 × 2.54 = 20.32cm