Screw Gauge - Its lecture note PDF

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Its lecture note...

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SCREW GAUGE AIM Our objective is to use the screw gauge;   

To measure the diameter of the given solid ball. To measure the diameter of a given wire. To measure the thickness of a given glass plate

APPARATUS Screw gauge, wire,glass plate,solid ball, scale

THEORY The screw gauge is an instrument used for measuring accurately the diameter of a thin wire or solid ball,the thickness of a sheet of metal or glass . It consists of a U-shaped frame fitted with a screwed spindle which is attached to a thimble.

Pitch of the Screw Gauge The pitch of the screw is the distance moved by the spindle per revolution. To find this, the distance advanced by the head scale over the pitch scale for a definite number of complete rotation of the screw is determined. The pitch can be represented as;

Least Count of the Screw Gauge The Least count (LC) is the distance moved by the tip of the screw, when the screw is turned through 1 division of the head scale. The least count can be calculated using the formula;

Dimension measured= Pitch scale reading + (corrected head scale reading x least count)

Volume of the wire = πr2 l where ,r is the radius of wire Volume of solid ball =4/3 πr3 where ,r is the of solid ball Volume of glass plate= lbt where ,l is the length of glass plate where ,b is the breadth of glass plate where ,t is the thickness of glass plate

OBSERVATIONS

1. Determination of Least Count of the Screw Gauge

1 Linear Scale Division, LSD = 1 mm Number of full rotations given to screw =4 Distance moved by the screw = 4mm

Hence , pitch p=

= 1mm

Number of divisions on circular scale=100

Hence, least count, L.C

=

= 0.01 mm= 0.001 cm

2. Zero Error

Zero error

=

Zero correction =

divisions divisions

OBSERVATIONS

Trial object

P.S.R (mm)

H.S.R

Corrected

P.S.R

H.S.R

+

Mean (mm)

(Corrected H.S.R x L.C) (mm) 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5 wire

wire

Glass Plate

Mean diameter of wire =

Mean thickness of Glass plate=

Solid ball

Mean diameter of solid ball=

Mean diameter of wire = Mean radius of wire

=

Volume of the wire = πr2 l

Glass Plate Thickness of glass plate t = length of glass plate l

=

Breadth of glass plate b = Volume of glass plate=lbt Solid ball

Mean diameter of solid ball = Mean radius of solid ball = Volume of solid ball =4/3 πr3

RESULT

Mean diameter of wire = Mean radius of wire

=

Volume of the wire

=

Thickness of glass plate t = Volume of glass plate = Mean diameter of solid ball = Mean radius of solid ball = Volume of solid ball =...