Page 94 - Physics - XI

Table for calculation of extension and load

S. Load on Micrometer Reading (cm) Extension for
No. hanger H Loading Unloading 2.0 kg wt
(kg wt) (a) (b) Mean reading = a+ b l (cm)
2
1. 0.0 l =
0
2. 0.5 l =
1
3. 1.0 l = l – l 0
4
2 l – l
4. 1.5 l = l – l 1
5
3
5. 2.0 l = 6 2
4 l – l 3
7
6. 2.5 l =
5
7. 3.0 l =
6
8. 3.5 l =
7
Mean extension for load 2.0 kg wt = l = ______ cm = ______ m

Calculations
MgL 20 98 . L
Y = N/m 2
rl r l
2
2
Put all the values of L, r, and l in S.I. units.
Graph
Plot a graph between load and extension taking Y
load on X-axis and extension on Y-axis. The graph
comes to be a straight line as shown in Fig. 1.3.
Find the slope of the straight line
L Q
QR l A
Slope = = Scale used on:
PR Mg Extension (cm) X-axis: 1 kg wt = .... unit

l Y-axis: 1 cm = .... unit
Use this value of the slope in the formula,
Mg P R
Mg L
Y and compute the value of Y. The X
l r 2 Load (kg wt)
values of r and L should be taken in metre.
Fig. 1.3: Graph between load and extension

Result
The Young modulus of the material (steel) of the wire by Searle's apparatus is ______ N/m .
2
Value of Y for steel from the table of constant = ______ N/m 2

Percentage of error = (Actual valueValue from the experiment) 100
Actual value
= ______ %

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