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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
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
Why does a galvanometer when connected in series with a capacitor show a momentary deflection, when it is being charged or discharged?
How does this observation lead to modifying the Ampere's circuital law?
Hence write the generalised expression of Ampere's law.
Define the current sensitivity of a galvanometer ?
Draw a labelled diagram of a moving coil galvanometer and explain its working. What is the function of radial magnetic field inside the coil?
Outline the necessary steps to convert a galvanometer of resistance RG into an ammeter of a given range ?
Why are the pole pieces of a horseshoe magnet in a moving coil galvanometer made cylinder in shape?
Explain the significance of a radial magnetic field when a current-carrying coil is kept in it.
Assertion (A): On Increasing the current sensitivity of a galvanometer by increasing the number of turns may not necessarily increase its voltage sensitivity.
Reason (R): The resistance of the coil of the galvanometer increases on increasing the number of turns.
Select the most appropriate answer from the options given below:
A voltmeter of variable ranges 3 V, 15 V, 150 V is to be designed by connecting resistances R1, R2, R3 in series with a galvanometer of resistance G = 20 Ω, as shown in Fig. The galvanometer gives full pass through its coil for 1 mA current i.e. "gives full pass through it's coil for 1 mA current". Then, the resistances R1, R2 and R3 (in kilo ohms) should be, respectively:
A resistance of 3Ω is connected in parallel to a galvanometer of resistance 297Ω. Find the fraction of current passing through the galvanometer.
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?
