Current Electricity and Electrical InstrumentMedium

Question

A galvanometer of resistance $100\Omega$ gives full scale deflection for a current of 1 mA . It is converted into an ammeter of range $0 - 10\text{ }A$. The shunt required is:

Options

A.$0.01\Omega$
B.$0.10\Omega$
C.$1.0\Omega$
D.$0.001\Omega$

Solution

Sol. [Key Concept: Galvanometer → ammeter using a shunt] $i_{G} = 1\text{ }mA = 0.001\text{ }A$

$$i_{S} = 10 - i_{G} \simeq 10\text{ }A$$

Both shunt resistance and galvanometer are in parallel connection

$$\begin{matrix} \therefore & i_{s}r_{s} = i_{G}R_{G} \\ \Rightarrow & 10 \times r_{s} = 0.001 \times 100 \\ \Rightarrow & r_{s} = 0.01\Omega \end{matrix}$$

In a meter bridge experiment (see figure), the positions of the cell, $E$, and galvanometer, $G$, are interchanged.

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