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Physics · 100 Level
This is the complete lecture note for PHY108 General Practical Physics II, prepared for Physics students at 100 Level. You can read it online below, open it in the full viewer, or download the PDF for offline study. It pairs with the course's video lectures, so you can read and watch together.
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LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Course Code: PHY 108 Course Title: General Practical Physics Course Unit: 1 Unit Series 1: Fundamentals of Physical Measurements Series 2: Observation and Data Handling Techniques Series 3: Experimental Errors and Evaluation Series 4: Graphical Analysis and Interpretation Series 5: Scientific Reporting and Presentation Skills Series 1: Fundamentals of Physical Measurements Series outline • 1.1 Basic Concepts of Measurement • 1.1.1 Physical Quantities and Units • 1.1.2 Standards of Measurement • 1.1.3 Importance of Accuracy and Precision • 1.2 Measurement Instruments and Techniques • 1.2.1 Common Laboratory Instruments (e.g., metre rule, vernier caliper, micrometer screw gauge) • 1.2.2 Proper Handling and Calibration • 1.2.3 Limitations of Instruments • 1.3 Recording and Interpreting Measurements • 1.3.1 Data Collection and Tabulation • 1.3.2 Estimation of Uncertainty • 1.3.3 Significance of Consistency in Results Introduction Measurements form the backbone of all experimental work in physics. Whether determining the length of a rod, the time taken for a pendulum to swing, or the mass of an object, the ability to measure accurately and consistently is what transforms observation into scientific knowledge. Without reliable measurements, data cannot be trusted, and conclusions drawn from experiments would lack validity. This Series therefore provides the foundation upon which all other practical work in physics is built. The aim of this Series is to equip you with the essential skills required to carry out physical measurements, to familiarise you with the instruments commonly used in the laboratory, and to guide you in recording and interpreting measured values with accuracy and precision. We shall commence this Series by examining the basic concepts of measurement, including physical quantities, units, and standards. Next, we will explore measurement instruments and techniques, focusing on how to use and calibrate common laboratory tools while recognising their limitations. Finally, we will wrap up by considering how to record and interpret measurements, including the estimation of uncertainty and the importance of consistency in results. This sequential approach will ensure that you gain both theoretical understanding and practical competence in the fundamentals of physical measurements.
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Series Learning Outcomes Upon completing this Series, you should be able to: • 1.1 define physical quantities and units, and explain their importance in measurement, • 1.2 describe standards of measurement and evaluate their role in ensuring accuracy, • 1.3 demonstrate the correct use of common laboratory instruments for basic measurements, • 1.4 apply appropriate techniques for handling and calibrating instruments, • 1.5 record measured values systematically and tabulate data clearly, • 1.6 analyse measurement results by estimating uncertainty and assessing consistency. 1.1 Basic Concepts of Measurement 1.1.1 Physical quantities and units In physics, we deal with physical quantities, which are measurable properties of matter or energy such as length, mass, time, and temperature. A physical quantity must be expressed as a numerical value followed by a unit, which is a standard reference used to compare measurements. For example, the length of a rod may be expressed as 2 metres, where “2” is the numerical value and “metre” is the unit. Fill in the blank: The measurable property of matter or energy that requires a numerical value and a unit is called __________. Figure 1.1: Measurement of length using a ruler 1.1.2 Standards of measurement A standard of measurement is an agreed reference used internationally to ensure consistency in scientific work. For instance, the metre is defined in terms of the distance light travels in a
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS vacuum during a specific fraction of a second. Standards are essential because they allow scientists across the world to compare results reliably. Fill in the blank: The agreed reference used internationally to ensure consistency in scientific work is called a __________. Unit Physical Quantity Symbol Modern Definition (since 2019) Metre Length m The length of the path traveled by light in a vacuum during a time interval of 1/299,792,458 of a second. Kilogram Mass kg Defined by taking the fixed numerical value of the Planck constant h to be $6.62607015 \times 10^{-34}$ when expressed in the unit $\text{J}\cdot\text{s}$, which is equal to $\text{kg}\cdot\text{m}^2\cdot\text{s}^{-1}$. Second Time s Defined by taking the fixed numerical value of the cesium frequency $\Delta\nu_{\text{Cs}}$, the unperturbed ground-state hyperfine transition frequency of the cesium-133 atom, to be $9,192,631,770$ when expressed in the unit Hz, which is equal to $\text{s}^{-1}$. Box 1.1: Examples of international standards 1.1.3 Importance of accuracy and precision Accuracy refers to how close a measurement is to the true value, while precision refers to how close repeated measurements are to each other. For example, if you measure the length of a rod several times and obtain values that are very similar, your measurements are precise. If those values are also close to the actual length, then they are accurate. Both accuracy and precision are vital in physics because they determine the reliability of experimental results. Fill in the blank: When repeated measurements are close to each other, this is referred to as __________.
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Figure 1.2: Difference between accuracy and precision Pilot questions 1.1 1. Define a physical quantity and give two examples. 2. What is the difference between a unit and a standard of measurement? 3. Explain why international standards of measurement are important in physics. 4. Distinguish between accuracy and precision with suitable examples. 5. Fill in the blank: A measurement that is close to the true value is said to be __________. 1.2 Measurement Instruments and Techniques 1.2.1 Common laboratory instruments In physics laboratories, several instruments are used to measure physical quantities. The metre rule is a simple instrument for measuring length, usually marked in centimetres and millimetres. The vernier caliper is used for more precise measurements of internal and external diameters, while the micrometer screw gauge is designed for measuring very small dimensions such as the thickness of a wire. Each of these instruments has a specific range and level of precision, making them suitable for different tasks. Fill in the blank: The instrument commonly used to measure very small dimensions such as the thickness of a wire is the __________.
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Figure 1.3: Common laboratory instruments for measurement 1.2.2 Proper handling and calibration Calibration is the process of adjusting an instrument to ensure its readings are accurate compared to a known standard. For example, a vernier caliper must be checked to ensure that its zero mark aligns correctly when closed. Proper handling of instruments is equally important. Learners should avoid parallax errors by ensuring their eyes are directly above the scale when taking readings. Instruments should also be kept clean and stored properly to maintain their accuracy. Fill in the blank: The process of adjusting an instrument to ensure its readings are accurate compared to a known standard is called __________. 1.1: Calibrating a vernier caliper
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS 1.2.3 Limitations of instruments Every measuring instrument has limitations, which are the constraints that affect its accuracy and precision. For instance, a metre rule cannot measure very small dimensions accurately because its smallest division is 1 millimetre. Similarly, a micrometer screw gauge may be unsuitable for measuring large objects due to its limited range. Recognising these limitations helps learners select the appropriate instrument for each measurement task. Fill in the blank: The smallest division on a metre rule is __________. Measuring Instrument Key Limitations Metre Rule Limited Precision: Its smallest division is typically 1 mm, which is not precise enough for many small-scale measurements. Parallax Error: Accurate readings depend on the user's line of sight being perpendicular to the scale, making it prone to human error. Vernier Caliper Requires Careful Calibration: The user must diligently check for zero error before use to avoid systematic measurement errors. Limited Range: It can only measure objects up to its maximum capacity, which is typically smaller than what a metre rule can handle. Micrometer Screw Gauge Unsuitable for Large Objects: Its physical design restricts its use only to very small dimensions (like diameters of wires, which you can see a student measuring here: ). Highly Precise, But... While very precise (typically 0.01 mm), this precision can be lost if not handled carefully, and it cannot replace a larger instrument when one is needed. Box 1.2: Limitations of selected instruments Pilot questions 1.2 1. Name three common laboratory instruments and state one use for each. 2. What is calibration and why is it important in measurement? 3. Explain how parallax error can be avoided when using a metre rule. 4. State one limitation of the micrometer screw gauge. 5. Fill in the blank: A vernier caliper is used to measure __________.
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS
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