Diffrence between dead beat and ballastic galvanometer... Can pls tell me this

To get information about the topic Ballistic galvanometer full report ppt and related topic refer the page link below

Ballistic galvanometer

A ballistic galvanometer is a type of sensitive galvanometer, commonly a mirror galvanometer. Unlike a current-measuring galvanometer, the moving part has a large moment of inertia, thus giving it a long oscillation period. It is really an integrator measuring the quantity of charge discharged through it. It can be either of the moving coil or moving magnet type.

Grassot Fluxmeter

An interesting form of ballistic galvanometer is the Grassot fluxmeter. In order to operate correctly, the discharge time through the regular ballistic galvanometer must be shorter than the period of oscillation. For some applications, especially those involving inductors, this condition cannot be met. The Grassot fluxmeter solves this. Its construction is similar to that of a ballistic galvanometer, but its coil is suspended without any restoring forces in the suspension thread or in the current leads. The core (bobbin) of the coil is of a non-conductive material. When an electric charge is connected to the instrument, the coil starts moving in the magnetic field of the galvanometer's magnet, generating an opposing e.m.f. and coming to a stop regardless of the time of the current flow. The change in the coil position is proportional only to the quantity of charge. The coil is returned to the zero position by the reversing of the current or manually.

Moving Coil Ballistic Galvanometer


Principle. When a current is passed through a coil, suspended freely in a magnetic field, it experiences a forces in a direction given by Fleming’s left hand rule.

Construction. It consists of a rectangular coil of thin copper wire wound on a non-metallic frame of ivory. It is suspended by means of a phosphor bronze wire between the poles of a powerful horse-shoe magnet. A small circular mirror is attached to the suspension wire. Lower end of the coil is connected to a hair-spring. The upper end of the suspension wire and the lower end of the spring are connected to terminals T1 and T2. A cylindrical soft iron core © is place symmetrically inside the coil between the magnetic poles which are also made cylindrical in shape. This iron core concentrates the magnetic field and helps in producing radial field.
The B.G. is used to measure electric charge. The charge has to pass through the coil as quickly as possible and before the coil stars moving. The coil thus gets an impulse and a throw is registered. To achieve this result, a coil of high moment of inertia is used so that the period of oscillation of the coil is fairly large. The oscillations of the coil are practically undamped.
Theory. (i) Consider a rectangular coil of N turns placed in a uniform magnetic field of magnetic induction B. Lel l be the length of the coil and b its breadth.