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प्रश्न
A multirange current meter can be constructed by using a galvanometer circuit as shown in figure. We want a current meter that can measure 10 mA, 100 mA and 1A using a galvanometer of resistance 10 Ω and that prduces maximum deflection for current of 1mA. Find S1, S2 and S3 that have to be used
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उत्तर
A galvanometer can be converted into ammeter by connecting a very low resistance wire (shunt S) connected in parallel with galvanometer. The relationship is given by IgG = (I – Ig) S, where Ig is the range of galvanometer and G is the resistance of galvanometer.
For measuring `I_1 = 10 mA: I_G.G = (I_1 - I_G)(S_1 + S_2 + S_3)`
For measuring `I_2 = 100 mA: I_G(G + S_1) = (I_2 - I_G)(S_2 + S_3)`
For measuring `I_3 = 1 A: I_G(G + S_1 + S_2) = (I_3 - I_G)(S_3)`
Gives `S_1 = 1 Ω, S_2 = 0.1 Ω`
And `S_3 = 0.01 Ω`
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संबंधित प्रश्न
Show that the current flowing through a moving coil galvanometer is directly proportional to the angle of deflection of coil.
Write the underlying principle of a moving coil galvanometer.
Explain how moving coil galvanometer is converted into a voltmeter. Derive the necessary formula.
A rectangular coil of a moving coil galvanometer contains 100 turns, each having area
15 cm2. It is suspended in the radial magnetic field 0.03 T. The twist constant of suspension
fibre is 15 x 10-10 N-m/degree. Calculate the sensitivity of the moving coil galvanometer.
A moving coil galvanometer has a resistance of 25Ω and gives a full scale deflection for a current of 10mA. How will you convert it into a voltmeter having range 0 - 100 V?
Why is it necessary to introduce a radial magnetic field inside the coil of a galvanometer?
Write current sensitivity of a galvanomete S.I. unit.
Explain, giving reasons, the basic difference in converting a galvanometer into (i) a voltmeter and (ii) an ammeter?
Draw a labelled diagram of a moving coil galvanometer and explain its working. What is the function of radial magnetic field inside the coil?
Define the term ‘current sensitivity’ of a moving coil galvanometer.
The deflection in a moving coil galvanometer is ______.
The current sensitivity of a galvanometer increase by 20%. If its resistance also increases by 25%, the voltage sensitivity will ______.
A galvanometer of resistance 100 Ω gives a full-scale deflection for a current of 10−5 A. To convert it into an ammeter capable of measuring up to 1 A we should connect a resistance of ______.
The coil of galvanometer consists of 100 turns and effective area of 1 square cm. The restoring couple is 10-8 N-m/rad. The magnetic field between the pole pieces is 5T. The current sensitivity of this galvanometer will be ______.
When a galvanometer is shunted with a 4 Ω resistance, the deflection is reduced to one-fifth. If the galvanometer is further shunted with a 2 Ω wire. The further reduction (find the ratio of decrease in current to the previous current) in the deflection will be (the main current remains the same)
A moving coil galvanometer has 150 equal divisions. Its current sensitivity is 10-divisions per milliampere and voltage sensitivity is 2 divisions per millivolt. In order that each division reads 1 volt, the resistance in ohms needed to be connected in series with the coil will be ______.
How is current sensitivity increased?
A voltmeter has a range of 0 - 20 V and a resistance of 500 Q. Explain how can be used to measure voltages from 0 - 200 volt?
A galvanometer of resistance 100 Ω gives a full-scale deflection for a potential difference of 200 mV.
- What must be the resistance connected to convert the galvanometer into an ammeter of the range 0-200 mA?
- Determine resistance of the ammeter.
