Name: Magnetic Dipole and Dipole Moment
Uploaded: 2019-07-19
Duration: 4 min 53 s
Description: A magnetic dipole is an arrangement of two unlike magnetic poles of equal pole strength separated by a minimal distance. Let's learn more about them.

Question

Define radial field and sensitivity of a moving coil galvanometer and also explain the factors on which current sensitivity of a suspended coil galvanometer depends.

Accepted Answer

Radial magnetic field: As the coil of moving coil galvanometer is placed between the cylindrical pole pieces of a strong permanent horse-shoe magnet and a cylindrical soft iron core is mounted between the concave pole pieces which makes the line of force pointing along the radius of the circle and the magnetic field is named as radial magnetic field.

The plane of coil rotating in such magnetic field remains parallel to the field in all position.

Sensitivity : A galvanometer is said to be sensitive if a small current passed through it produces a sufficiently large deflection. The sensitivity is of two types : current sensitivity and voltage sensitivity.

The current sensitivity of a galvanometer is defined as the deflection produced in the galvanometer when a unit current flows through it.

i.e. $I_{s} = \frac{ϕ}{I}$ . But $\frac{ϕ}{I} = \frac{NAB}{C}$ $\Rightarrow I_{s} = \frac{NAB}{C}$
The voltage sensitivity of a galvanometer is defined as the deflection produced in the galvanometer when a unit voltage is applied across its coil.

If a voltage $V$ produces a deflection $ϕ$ in the galvanometer, then the voltage sensitivity is $V_{s} = \frac{ϕ}{V}$ $= \frac{ϕ}{IR} .$ $\Rightarrow V_{s} = \frac{NAB}{CR}$

Factors on which the sensitivity of galvanometer depends: On the basis of expression of sensitivity of galvanometer it can be said that sensitivity depends upon

$1 .$ The number of turns in the coil $(N)$

$2 .$ The strength of magnetic field $(B)$

$3 .$ The area of the coil $(A)$ and

$4 .$ The torsion constant of suspension $(C)$

Define radial field and sensitivity of a moving coil galvanometer and also explain the factors on which current sensitivity of a suspended coil galvanometer depends.

Important Questions on Torque on a Current-Loop : Moving-Coil Galvanometer

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