# Cm Vernier Scale

Topics: Vernier scale, Micrometer, Orders of magnitude Pages: 78 (25595 words) Published: November 3, 2014
Base quantity 1A physical quantity is .. 2Examples of scientific instruments stopwatch, metre rule, triple beam balance, thermometer, ammeter, voltmeter, spring balance, etc. 3A base quantity is a physical quantity which cannot be defined to other physical quantities. 5List of 5 basic physical quantities and their units. i) Light intensity unit candela ii) Amount of substance unit mol Derived quantities 1A derived quantity is a physical quantity which combines several basic quantities through multiplication, division or both. 2Determine the derived unit for the following derived quantities. t EMBED Equation.3 ForceFforce mass x acceleration F makg m s-2Newton (N)pressureP EMBED Equation.3 , P F/AN m-2Pascal (Pa)weightWweight mass x gravitational acceleration W mgkg m s-2Newton (N)workWwork force x displacement W FsN mJoule (J)powerP EMBED Equation.3 , P W/t , P E/tJ s-1Watt (W)kinetic energyEk EMBED Equation.3 Ek mv2kg m2 s-2Joule (J)potential energyEpP.E mass x gravitational acceleration x height 2.It will be written before the unit as a multiplying factor. 3.The list of prefixes 4.Some physical quantities have extremely large magnitudes. These extremely large and small values can be written in standard form or using standard prefixes. Write the quantities in standard prefixes a.Frequency of radio wave 91 000 000 Hz 9.1 x 10 1MHz b.Diameter of the earth 12 800 000 m 12.8 Mm 1.28 x 10 1 Mm c.Distance between the moon and the earth 383 000 000 m 383 Mm 3.83 x 10 2 Mm d.Mass of the earth 6 000 000 000 000 000 000 000 000 kg 6.0 x 10 12 Tm Standard Form 1Standard form A x 10n, 1 A 10 and n integer 2Standard form is used to simplify the expression of very large or small numbers 3Some physical quantities have extremely small magnitudes. Write them in standard form Radius of the earth 6 370 000 m 6.37 x 106 m Mass of an electron 0.000 000 000 000 000 000 000 000 016 73 kg 1.673 x 10-27 kg c.Size of a particle 0.000 03 m 3.0 x 10-4 m b.Diameter of an atom 0.000 000 072 m 7.2 x 10-8 m c. Wavelength of light 0.000 000 55 m 5.5 x 10-7 m SCALAR AND VECTOR QUANTITIES 1Scalar quantities are quantity which has only magnitude only Examples Mass, Length, Speed, volume, distance 2Vector quantities are quantity which has magnitude and direction Examples Velocity, Force, Displacement, Acceleration 2We must know how to choose the appropriate instrument to measure a particular quantity 3Examples of instrument and its measuring ability. Measuring instrumentRange of measurementSmallest scale divisionMeasuring tapeUp to a few meters1 cmMeter rule1 m0.1 cmVernier caliper13 cm0.01 cmMicrometer screw gauge2.5 cm (25 mm)0.01 mm (0.001 cm)4Sample of measuring instruments 4.1Ammeter is use to measure electric current Measuring cylinder is use to determine the volume of liquid Ruler is use to determine the length Vernier calliper is used to measure a.small object b. depth of a hole c.external diameter of a cylinder or pipe d. internal diameter of a pipe or tube A vernier calliper gives readings to an accuracy of 0.01 cm. Length of vernier scale 0.9 cm Vernier scale is divided into 10 divisions Length of the divisions 0.09 cm The diagram below shows a vernier calliper with reading. Vernier calliper reading 0.15 cm 4.5Micrometer screw gauge. A micrometer screw gauge is used to measure a.objects that are small in size b.diameter of a wire c.diameter of small spheres such as ball bearings Function of ratchet to prevent from exerting too much pressure on the object. 4.6 Some others measuring instruments .. . .. Hands-on activity 1.1 on page 1 of the practical book to learn more about choosing appropriate instruments....