Page 141 - Physics - XII

11. Take four more sets of reading by changing the value of current.
12. Plot the graph between I and θ by taking them along X-and Y-axes, respectively.
13. At last, measure the inner and outer diameters of the coil by using a metre scale at least three times.

Then Radius, R = d
2
d d
where, diameter, d 1 2 and d and d represents inner and outer diameters of tangent galvanometer,
2 1 2
respectively.

Observations

Number of turns used, N = _____
Range of ammeter = 0 to _____ A
Least count of ammeter = _____ A
Zero error in ammeter = _____ A
R R R
Mean radius of the coil, R 1 2 3 = _____ cm
2
Table for Variation of θθ with I
Value of defl ection θθ (degree) Ammeter reading,

S. For current in one For current in reverse Mean θθ I (A)
No. direction direction (degree) tanθθ
θ θ θ θ θ θ θ θ Observed Corrected
1 2 3 4
1.

2.
3.

4.
5.

Table for Radius of Tangent Galvanometer (R)

Mean diameter,
S. Inner diameter, Outer diameter, d+ d Radius, R= d (cm)
No. d (cm) d (cm) d= 1 2 (cm) 2
1 2 2

1. R = _____ cm
1
2. R = _____ cm
2
3. R = _____ cm
3

Graph and Calculations
Plot the graph between I and tanθ. The graph shows a straight line.
From graph,

Slop of the straight line, m = BC
AC
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