Grinnell College Physics Museum

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Astatic Galvanometer with Glass Dome

A galvanometer is a device for detecting electric current. The galvanometer pointer deflection is from electric current passing through a coil immersed in a magnetic field from permanent magnets.

Ballistic Galvanometer

Like many other galvanometers, a ballistic galvanometer has a coil which rotates between magnets. The ballistic galvanometer has the special feature that its rotating coil has a large moment of inertia. It is used to measure quantity of charge rather than currents, for the large moment of inertia permits the passage of a quantity of charge before the coil moves significantly. The passage of the charge produces an impulse, a momentary torque, which causes the coil then to swing slowly to some maximum position. Such a galvanometer was often used to standardize capacitors. This galvanometer was purchased from Queen and Company for $75. probably near 1900.

Galvanometer

A galvanometer is a device for detecting electric current. The galvanometer pointer deflection is from electric current passing through a coil immersed in a magnetic field.

Galvanometer with Three Horseshoe Magnets

These two galvanometers each have three horseshoe magnets. The coil beside each magnet should be suspended vertically between the poles of the magnets.