Edexcel IAL as Physics Revision Guide Unit 1A

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Working as a Physicist Chapter 1

Before starting this course, you should be able to: 1.1  Quantities, Units & Symbols 1.1.1  Base quantities & units

! distinguish between quantities and units. ! recall the seven base quantities. 1.1.2  Derived quantities & units

! to reduce a derived unit to its base unit equivalents. 1.1.3  Unit prefixes

familiar unitthe prefixes ! be extreme to with other. from  pico at one tera at 1.2  Practical Skills 1.2.1  Measurements & uncertainties

! be aware of uncertainties in all measurements. ! understand the di"erence between precision and accuracy. ! estimate uncertainties in measurements. ! distinguish between systematic and random errors.

! calculate percentage uncertainties in measurements. ! determine percentage di"erence between result and accepted values. ! to choose appropriate measuring instruments. 1.2.2  Criticise results tables

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Section 1 . 1

1.1.1 Base quantities & units something you can measure directly directly.. !  A base quantity is something th e candela in this course.) ! There are seven base quantities. (We will not be concerned with the

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1.1.2 Derived quantities & units can be derived from basic basic quantities. !  All other quantities can

! For example, speed is found by dividing length by time. The unit is also derived, namely metre per second or ms-1. ! The units we use are called S.I. units (système internationale) ! SI units must be used in equations, even though sometimes it is convenient to use other units, like cm instead of m, or g instead of kg.

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