Measurement

Question What is measurement? tap to flip ↻ Answer The process of comparing an unknown quantity with a known standard unit to determine its magnitude. Question What is a physical quantity? tap to flip ↻ Answer A property of an object or phenomenon that can be measured and expressed in numbers with units. Question What are fundamental quantities? tap to flip ↻ Answer Basic quantities that are independent of each other and cannot be derived from other quantities. Question Name the seven fundamental quantities in the SI system. tap to flip ↻ Answer Length, mass, time, electric current, thermodynamic temperature, amount of substance, and luminous intensity. Question What are derived quantities? tap to flip ↻ Answer Quantities obtained by combining fundamental quantities through multiplication or division. Question What is the SI unit of length? tap to flip ↻ Answer Metre (m) Question What is the SI unit of mass? tap to flip ↻ Answer Kilogram (kg) Question What is the SI unit of time? tap to flip ↻ Answer Second (s) Question What is the SI unit of electric current? tap to flip ↻ Answer Ampere (A) Question What is the SI unit of thermodynamic temperature? tap to flip ↻ Answer Kelvin (K) Question What is the SI unit of amount of substance? tap to flip ↻ Answer Mole (mol) Question What is the SI unit of luminous intensity? tap to flip ↻ Answer Candela (cd) Question What is a standard unit? tap to flip ↻ Answer A fixed, internationally accepted quantity used as a reference for measurement. Question Why do we need standard units? tap to flip ↻ Answer To ensure consistency, accuracy, and reproducibility in measurements worldwide. Question What is the SI system? tap to flip ↻ Answer The International System of Units, a globally accepted system of measurement based on seven fundamental units. Question What is a metre scale used to measure? tap to flip ↻ Answer Length up to 1 metre, typically with a least count of 1 mm. Question What is the least count of a measuring instrument? tap to flip ↻ Answer The smallest measurement that can be read accurately on the instrument. Question What is the least count of a typical Vernier caliper? tap to flip ↻ Answer 0.1 mm or 0.01 cm Question What is the least count of a screw gauge? tap to flip ↻ Answer 0.01 mm or 0.001 cm Question What is parallax error? tap to flip ↻ Answer An error that occurs when the observer's eye is not directly in line with the measurement reading. Question How can parallax error be minimized? tap to flip ↻ Answer By positioning the eye directly above the measurement mark and using a mirror scale if available. Question What is the SI unit of area? tap to flip ↻ Answer Square metre ($\text{m}^2$) Question What is the SI unit of volume? tap to flip ↻ Answer Cubic metre ($\text{m}^3$) Question What is the SI unit of speed? tap to flip ↻ Answer Metre per second ($\text{m/s}$) Question What is the SI unit of density? tap to flip ↻ Answer Kilogram per cubic metre ($\text{kg/m}^3$) Question What is the formula for density? tap to flip ↻ Answer $\text{Density} = \frac{\text{Mass}}{\text{Volume}}$ Question What is the formula for speed? tap to flip ↻ Answer $\text{Speed} = \frac{\text{Distance}}{\text{Time}}$ Question What is the difference between mass and weight? tap to flip ↻ Answer Mass is the amount of matter in an object (constant), while weight is the force of gravity on it (varies with gravity). Question What is the SI unit of weight? tap to flip ↻ Answer Newton (N) Question What is the relation between weight and mass? tap to flip ↻ Answer $W = m \times g$, where $W$ is weight, $m$ is mass, and $g$ is acceleration due to gravity. Question What is the approximate value of $g$ on Earth's surface? tap to flip ↻ Answer $9.8\ \text{m/s}^2$ Question What is the difference between accuracy and precision? tap to flip ↻ Answer Accuracy refers to how close a measurement is to the true value, while precision refers to how close repeated measurements are to each other. Question What is a systematic error? tap to flip ↻ Answer An error that consistently occurs in the same direction due to faulty instruments or incorrect measurement techniques. Question What is a random error? tap to flip ↻ Answer An unpredictable error that varies in magnitude and direction, often due to environmental fluctuations or human limitations. Question How can systematic errors be reduced? tap to flip ↻ Answer By calibrating instruments, using correct measurement techniques, and applying zero-error corrections. Question How can random errors be reduced? tap to flip ↻ Answer By taking multiple measurements and calculating the average. Question What is the significance of significant figures? tap to flip ↻ Answer They indicate the precision of a measurement and help in reporting results honestly. Question How many significant figures are in 0.00520? tap to flip ↻ Answer Three Question What is the rule for rounding off numbers? tap to flip ↻ Answer If the digit to be dropped is less than 5, round down; if 5 or more, round up. Question What is the SI unit of force? tap to flip ↻ Answer Newton (N) Question What is the SI unit of pressure? tap to flip ↻ Answer Pascal (Pa) Question What is the formula for pressure? tap to flip ↻ Answer $\text{Pressure} = \frac{\text{Force}}{\text{Area}}$ Question What is the SI unit of work? tap to flip ↻ Answer Joule (J) Question What is the SI unit of power? tap to flip ↻ Answer Watt (W) Question What is the formula for power? tap to flip ↻ Answer $\text{Power} = \frac{\text{Work}}{\text{Time}}$ Question What is the SI unit of frequency? tap to flip ↻ Answer Hertz (Hz) Question What is the SI unit of electric charge? tap to flip ↻ Answer Coulomb (C) Question What is the SI unit of electric potential difference? tap to flip ↻ Answer Volt (V) Question What is the SI unit of resistance? tap to flip ↻ Answer Ohm ($\Omega$) Question What is the SI unit of energy? tap to flip ↻ Answer Joule (J) Question What is the difference between distance and displacement? tap to flip ↻ Answer Distance is the total path length (scalar), while displacement is the shortest straight-line distance with direction (vector). Question What is the difference between speed and velocity? tap to flip ↻ Answer Speed is scalar (magnitude only), while velocity is vector (magnitude with direction). Question What is the formula for average speed? tap to flip ↻ Answer $\text{Average speed} = \frac{\text{Total distance}}{\text{Total time}}$ Question What is the formula for acceleration? tap to flip ↻ Answer $\text{Acceleration} = \frac{\text{Change in velocity}}{\text{Time taken}}$ Question What is the SI unit of acceleration? tap to flip ↻ Answer Metre per second squared ($\text{m/s}^2$) Question What is the difference between scalar and vector quantities? tap to flip ↻ Answer Scalar quantities have only magnitude, while vector quantities have both magnitude and direction. Question Give two examples of scalar quantities. tap to flip ↻ Answer Mass and temperature (or distance, speed, time, etc.) Question Give two examples of vector quantities. tap to flip ↻ Answer Displacement and velocity (or force, acceleration, etc.) Question What is the SI unit of temperature? tap to flip ↻ Answer Kelvin (K) Question How is the Kelvin scale related to the Celsius scale? tap to flip ↻ Answer $T(\text{K}) = T(^\circ\text{C}) + 273.15$ Question What is the freezing point of water in Kelvin? tap to flip ↻ Answer 273.15 K Question What is the boiling point of water in Kelvin at 1 atm? tap to flip ↻ Answer 373.15 K