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WHAT IS PHYSICS?

From Greek word physikos

IS A BRANCH OF SCIENCE CONCERNING THESTUDY ABOUTNATURAL PHENOMENAAND

PROPERTIES OF MATTER


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Field ofstudy inPhysics

Force andmotion

Radioactivity

Heat

Light

Forces andpressure

Electricand

Electronic

Wave

Electromagnetism


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Physical quantity Is a quantity that can be measured Eg: mass, length, volume, temperature

Base quantity Derived quantity

Is a quantity that cannotbe derived in other base

quantity.

Is a quantity that can bederived from other base

quantity bymultiplication ordivision.


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Prefixes Use to represent physical quantitieswhich are very big

or very small in S.I units.

Prefix Symbol

Multiplicationfactor

Value

Tera T 1012 1 000 000 000

000

Giga G 109 1 000 000 000

Mega M 106 1 000 000

Kilo k 103 1000

Deci d 10-1 0.1

Centi c 10-2 0.01

Milli m 10-3 0.001

Micro 10-6 0.000001

Nano n 10-9 0.000000001

Pico p 10-12 0.000000000001


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Scientific notation/ Standard

form Numerical values which very small or big can be

written in standard form:

A 10n

(1 A < 10, positive or negative integer)Exercises:

1) Write 0.0000008 in scientific notation.

2) The equatorial diameter of earth is 12 760 000 m.Write the diameter in standard form.


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Conversion unitConvert the measurement:

a) 5.7 cm to metre

b) 1.5 km to metre

c) 1.1 g cm-3to kg m-3

d) 1.45 10-2Mm to me) 2.25 1010m to m

f) 2.2 108Gm to m

g) 36 kmh

-1

to ms

-1

h) 8 cm2to km2

i) 16 m2to cm2

j) 8.1 kgm-3to gcm-3

k) 25 ms-1to kmh-1


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1.3.1 Measure physical quantity

using appropriate instruments.a) Metre rule

Function Sensitivity

Measure lengthfrom a few cm

up to 1m

0.1 cm

b) Thermometer


Measure temperature. 1oC / 2oCc) Stopwatch


Measure time intervals. 0.1 s to 0.2 s


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d) Ammeter


Measure electric current. 0.1 A / 0.2 A

e) Voltmeter


Measurepotential difference /voltage.

0.1 V / 0.2 V

f) Measuring tapeFunction Sensitivity

Measure long distance,

circumference of round object.

1.0 cm


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g) Vernier callipers


Measure length, diameter innerand outer and depthobject with

dimension up to12.0 cm.

0.01 cm


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Function

Main scale Scale of 0.1 cm to 12 cmInside jaws Measure internal diameter

Outside jaws Measure external diameter and length

Tail Measure depth


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How to take reading of vernier callipers?1. Read main scale reading

Observe the zero mark 0on vernier scale.

The vernier scale lies between 1.2 cm and 1.3 cm.

Reading on main scale is 1.2 cm.

2. Read vernier scale reading Read mark on vernier scale that is exactly in linewith

any mark on main scale.

Reading on vernier scale= 0.03 cm


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Reading = Reading on + Reading onmain scale vernier scale

= 1.2 + 0.03 cm= 1.23 cm

Main scale

Vernierscale


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h) Micrometer Screw Gauge

Function SensitivityMeasure thickness or diameter

of small object in rangebetween 0.10 mm and 25.00

mm.

0.01 mm or 0.001 cm


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Function

Anvil and spindle Used to grip object.

Sleeve Main scale

Thimble Thimble scale

Ratchet knob Used to prevent exceeding pressure


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1. Read main scale reading Read main scale at edge of

thimble

Reading main scale = 5.5mm

2. Read thimble scale reading

Thimble scale reading =

0.28 mm

How to take reading of micrometer screw

gauge?

Reading = Main scale + Thimble scale

= 5.5 + 0.28

= 5.78 mm


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The smaller the change which can be measured byinstrument, the more sensitivethe instrument is.

The smallest scale divisionon measuring instruments

is the more sensitive the instrument is. Different measuring instruments have different levels

of sensitivity.

1.3.2 Explain Sensitivity

Sensitivity of an instruments is its ability todetect small changein the quantity to be

measured.


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Which one is more sensitive?


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1.3.2 Explain Accuracy and

ConsistencyACCURACY CONSISTENCY

Is how close the value of themeasurement to the actual

value.

Ability to register the samereading.

Consistence InconsistenceAccurate

Inaccurate


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ACCURACY CONSISTENCY

How to improveaccuracy:1. Repeat the

experiment and takeaverage reading.

2. Avoid zero error.

3. Avoid parallax error.4. Use measuringinstrument with highsensitivity.

How to improveconsistency:1. Avoid parallax error.


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Consistence butnot accurate

Accurate butinconsistence

Inaccurate andInconsistence

Accurate andconsistence

1 3 3 Explain Types of


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SYSTEMATIC ERROR RANDOM ERROR

1. Zero error Incorrect position of zero point

of measuring instrument.2. Incorrect calibration

Error in calibration ofinstrument which makes theinstrument defective.

- Systematic error will lead to

decrease in accuracy.

1. Parallax error error because of the observers

eyes.2. Natural error

change in temperature,humidity etc when experimentin progress

3. Wrong technique apply excessive pressure.

- Random error will lead to decreasein consistency.

How to reduce systematic error:Correct reading

= reading obtained - zero error

How to reduce random error:Repeat the experiment and take

average reading.

1.3.3 Explain Types of

Experimental Error


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Zero error


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Parallax error


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How to eliminate zero error?

Micrometer Screw Gauge

Negative zero errorZero error= -0.04 mm

Positive zero errorZero error= 0.02 mm


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Vernier Callipers

No zero error

Negative zero error

Positive zero error

zero error = 0.04 cm

zero error = 0 02 cm

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