1.1 the realm of physics

8/12/2019 1.1 the Realm of Physics

1/4

IB PHYSICS-Physics and Physical measuremen

TOPIC: 1

PHYSICS AND PHYSICAL MEASUREMENT

1.1 THE REALM OF PHYSICS

1. PHSICAL QUANTIITES: The quantities which can be measured, analyzed andsubjected to mathematical manipulation are called physical quantities.

2. FUNDAMENTAL PHYSICAL QUANTITIES: The physical quantities which do not

depend upon any other quantities for their measurement are called fundamental

quantities. There are seven fundamental physical quantities, they are

(i) Length

(ii) Ma

(iii) Ti!e

(i") Te!#e$at%$e

(") E&e't$i' '%$$ent

("i) L%!in% intenit an*

("ii)A!%nt + %,tan'e.

In addition to the fundamental physical quantities there are two quantities calledsupplementary quantities(i) P&ane ang&e an*(ii) S&i* ang&e

. Unit + !ea%$e!ent: The standard used for the measurement of a physical

quantity is called the unit of that physical quantity. The requirement of a !ood unit

are

"i# The unit should be invariable

"ii# It should be easily reproducible

"iii# The unit should be universally accepted.

1.1 THE REALM OF PHYSICS Page 3


2/4


The most commonly used system of units are

"i# $%& system and

"ii# &I " system international# system

'. (undamental quantities and their base units in &I system

N F%n*a!enta&-%antit

SI ,ae%nit

S!,&

1. )en!th metre m

2. *ass +ilo!ram +!

. Time second s'. Temperature +elvin

-. lectric current ampere /

0. )uminous intensity candela cd

. /mount ofsubstance

ilomole +mol

&upplementary quantities and their base units

N %##&e!enta$

-%antit

SI ,ae

%nit

S!,&

1. lane an!le radian rad

2. &olid an!le steradian sr

-. De$i"e* -%antitie: The quantities which depend on two or more fundamental

quantities for their measurement are called derived quantities.

&ome of the derived quantities and their &I units are

N. Phi'a& -%antit SI %nit S!,&

1. (orce 3ewton 3

2. 4or+, ener!y 5oule 5

. ower 4att 4

'. lectric char!e $oulomb $



3/4


-. lectric potential 6olt 6

0. lectric resistance 7hm 8

. (requency 9ertz 9z

. *a!netic flu; 4eber 4b

2

0. O$*e$ + !agnit%*e: The order of ma!nitude of a physical quantity is defined as

the power of ten nearest to that number.

N%!,e$ O$*e$ + !agnit%*e

1==

/ 0 1/1 1=1

// 0 1/2 1=2

.3 0 .3 1// 1==

4./ 0 4 1// 1=1

5 1/2 1=2-

3 1/671 1=>=

8. P9e$ #$e+i an* !,&

PO;ER PREFI< SYM=OL PO;ER PREFI< SYM=OL

1/61> att6 a 1/1 *e?a6 *a

1/614 +e!t6 + 1/2 he't6 h

1/612 #i'6 # 1/7 ?i&6 ?

1/63 nan6 n 1/5 !ega6 M

1/65 !i'$6 @ 1/3 giga6

1/67

!i&&i6 ! 1/12

tet$a6 T1/62 'enti6 ' 1/14 #eta6 P

1/61 *e'i6 * 1/1> ea6 E



4/4



1.1 the realm of physics

Documents