Torque on the Loop Placed in a Magnetic Field and Moving Coil Galvanometer

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 magnetic needle suspended parallel to a magnetic field requires $\sqrt{3} \mathrm{J}$ of work to turn it through $60°$. The torque needed to maintain the needle in this position will be

Explain the construction of moving coil galvanometer?

Write the definition of figure of merit of Galvanometer.

A moving coil galvanometer has the following characteristics- Number of turns of coil$=50$, Area of coil$=70{\mathrm{mm}}^2$, Resistance of coil$=30 \Omega$, the flux density of radial field$=0.1\mathrm{T}$, Torsional constant of suspension wire$=7\times {10}^{-8}\mathrm{Nm}/\mathrm{rad}$. Calculate the voltage sensitivity. 

The voltage sensitivity is defined as the deflection per unit current.

What is the SI unit of the voltage sensitivity?

Write the expression of the voltage sensitivity.

A moving coil galvanometer produces deflection $20.5\mathrm{rad}$ for current $10\mathrm{\mu A}$. Calculate current sensitivity?

The SI unit of current sensitivity in galvanometer is

A convenient way for the manufacturer to increase the current sensitivity is to increase the number of turns in the galvanometer.

Write the expression for the sensitivity of the ammeter.

If an ammeter is to be used in place of a voltmeter, then with the ammeter we must connect a,

What resistance should be connected in series of a galvanometer of resistance $R_g$ in order to change its range from $V$ volts to $N\mathrm{V}$ volts (in $\mathrm{ohm}$)

A galvanometer with a scale divided into $100$ equal divisions has a current sensitivity of $10 \text{divisions per milliampere}$ and a voltage sensitivity of $2\text{ divisions per millivolt}$. The galvanometer resistance will be,

A voltmeter has a $25 \mathrm{\Omega }$ coil and $575 \mathrm{\Omega }$ in series. The coil takes $10\mathrm{ }\mathrm{m}\mathrm{A}$ for full-scale deflection. The maximum potential difference which can be measured is 

A circular loop with $N$ turns has radius $r$. It lies in x-y plane carrying current $I$ in anti-clockwise direction. If the magnetic field in the region is $\overrightarrow{B}=B_0\widehat{i},$ then find the torque $\left(\overrightarrow{\tau }\right)$ acting on the loop.

A rectangular coil of a moving coil galvanometer contains $50 \mathrm{turns}$ each having area $12 {\mathrm{cm}}^2$. It is suspended in radial magnetic field $0.025 \mathrm{Wb}/{\mathrm{m}}^2$ by a fibre of twist constant $15\times {10}^{-10} \mathrm{Nm}/\mathrm{degree}$. Calculate the sensitivity of a moving coil galvanometer.

The combined resistance of galvanometer of resistance $1000 \mathrm{\Omega }$ and its shunt is $25 \mathrm{\Omega }$. Calculate the value of shunt.