Moving Coil Galvanometer

Statement -1: The sensitivity of a moving coil galvanometer is increased by placing a suitable magnetic materials as a core inside the coil.

Statement -2: Soft iron has a high magnetic permeability and cannot be easily magnetized or demagnetized.

In a moving coil galvanometer, the torque on the coil can be expressed as $\mathrm{\tau }=\mathrm{ki}$, where $\mathrm{i}$ is the current through the wire and $\mathrm{k}$ is a constant. The rectangular coil of the galvanometer having number of turns $\mathrm{N}$, area $\mathrm{A}$, and moment of inertia $\mathrm{I}$, is placed in magnetic field $\mathrm{B}$. Find the torsional constant of the spring, if a current ${\mathrm{i}}_0$ produces a deflection of $\frac{\pi }{2}$ in the coil in reaching the equilibrium position.

A moving coil galvanometer on connecting with a high resistance in series is converted into:

Two tangent galvanometers $A$ and $B$ have coils of radii $8 \mathrm{cm}$ and $16 \mathrm{cm}$ respectively and resistance $8 \mathrm{\Omega }$ each. They are connected in parallel with a cell of emf $4 \mathrm{V}$ and negligible internal resistance. The deflections produced in the tangent galvanometers $A$ and $B$ are $30° \text{and} 60°$ respectively. If $A$ has $2$ turns, then the number of turns $B$ must have is

A galvanometer of resistance $\mathrm{30 }\mathrm{\Omega }$ is connected to a battery of emf $\mathrm{2\; V}$ with $\mathrm{1970 }\mathrm{\Omega }$ resistance in series. A full scale deflection of $20$ divisions is obtained in the galvanometer. To reduce the deflection to $10$ divisions, the resistance in series required is____$\mathrm{\Omega }$.

The deflection in galvanometer falls to ${\left(\frac{1}{4}\right)}^{th}$, when it is shunted by $3 \Omega$ . If additional shunt of $\mathrm{2 \Omega }$ is connected in parallel to earlier shunt, the deflection in galvanometer falls to ${\left(\frac{1}{\alpha }\right)}^{th}$ value. Write the value of $2\alpha$.

A galvanometer having a coil resistance of $100\mathrm{ }\mathrm{\Omega }$ gives a full-scale deflection, when a current of $1 \mathrm{mA}$ is passed through it. The value of the resistance, which can convert this galvanometer into an ammeter giving a full scale deflection for a current of $10 \mathrm{A}$, is:

A galvanometer has current sensitivity of $10$ divisions per milliampere with $150$ equal divisions. Find shunt resistance required to convert given galvanometer into an ammeter of range $6 \mathrm{A}$?

A galvanometer has current sensitivity of $10$ divisions per $\mathrm{mA}$ with $150$ equal divisions. The shunt resistance in $\mathrm{m\Omega }$ required to convert given galvanometer into an ammeter of range $6 \mathrm{A}$ is $x$. Write the value of $10x$ to the nearest integer. Here, galvanometer voltage is $75 \mathrm{mV}$.

A galvanometer has $36 \mathrm{\Omega }$ resistance. If a $4 \mathrm{\Omega }$ shunt is added to this, the fraction of current that passes through the shunt is:-

In order to increase the sensitivity of galvanometer,

The thermo e.m.f of the copper-constantan couple is $40 \mathrm{\mu V}$ per degree. The smallest temperature difference that can be detected with this couple and a galvanometer of $100 \mathrm{\Omega }$ resistance capable of measuring the minimum current of $1 \mathrm{\mu A}$ is:

In a Radial Magnetic field:

Phosphor-bronze strip in a suspended coil galvanometer is used as a suspension fibre :

The maximum current in a galvanometer can be $10 \mathrm{mA}$. It's resistance is $10\mathrm{\Omega }$. To convert it into an ammeter of $1 \mathrm{A}$, a resistor should be connected in

When a galvanometer is shunted with a $4 \mathrm{\Omega }$ resistance, the deflection is reduced to one-fifth. If the galvanometer is further shunted with a $2 \mathrm{\Omega }$ wire, find the ratio of decrease in current to the previous current (the main current remains the same).

Two galvanometers A and B requires $2 \mathrm{mA}$ and $3 \mathrm{mA}$ current, respectively to produce the same deflection of $10$ division. Then

Two moving coil galvanometers, $X$ and $Y$ have coils with resistances $10 \mathrm{\Omega }$ and $14 \mathrm{\Omega }$, cross-sectional areas $4.8\times {10}^{-3} {\mathrm{m}}^2$ and $2.4\times {10}^{-3} {\mathrm{m}}^2$, number of turns $30$ and $45$ respectively. They are placed in magnetic fields of $0.25 \mathrm{T}$ and $0.50 \mathrm{T}$ respectively. Then the ratio of their current sensitivities and the ratio of their voltage sensitivities are respectively.

In the case of a moving coil galvanometer, the deflection is

To verify Ohm's law, a student is provided with a test resistor $R_T,$ a high resistance $R_1,$ a small resistance $R_2,$ two identical galvanometers $G_1$ and $G_2,$ and a variable voltage source $\mathrm{V}.$. The correct circuit to carry out the experiment is:-