Page 35 - Physics - XII

I
10. Least count of the converted ammeter = = _____ ampere
n
11. Least count of the standard ammeter = _____ ampere

Table for the verifi cation of the converted ammeter

Galvanometer Reading Standard voltmeter Diff erence (Error)
reading I I – I
S. No. Defl ection Current in ampere (amp) 2 2 1
θ θ I = θθ × L.C. (amp)
1
(division) (amp)

1.
2.

3.

4.

Calculations
I G
1. Calculation for shunt resistance, S g
I I g

On putting the values of I , G, and I, compute the value of S.
g
2
rS
2. Calculation for length of the wire, l

On putting the values of r, S, and ρ, calculate the required length l of the wire.

Result
1. Value of the shunt resistance required to convert the given galvanometer into an ammeter = _____ Ω
2. Required length of the given wire = _____ cm
3. As I – I is very small, hence, conversion of the given galvanometer into an ammeter of the given range
2
1
is verifi ed.
Precautions
1. All the connections should be neat, clean, and tight.
2. The shunt wire used should have a length of 2 cm more than required length which is being used under
the terminals.

3. The diameter of the wire to be used for shunt resistance should be measured accurately.
4. The ammeter used for the verifi cation should have the same range as converted ammeter.
5. The e.m.f. of the battery should be constant.

Sources of Error
1. The galvanometer divisions may not be of equal size.

2. The e.m.f. of the battery may not be constant.
3. There may be backlash error in the screw gauze.

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