The most sensitive galvanometer is the spot ballistic galvanometer. It is a type of galvanometer that uses a spot of light to measure the current flowing through it. The spot of light is reflected off of a mirror that is attached to a coil of wire. When current flows through the coil, the mirror rotates, and the spot of light moves across a scale. The more current that flows through the coil, the further the spot of light moves.
The spot ballistic galvanometer is very sensitive because it can detect very small changes in current. It is used in a variety of applications, including measuring the current in electrical circuits and the intensity of light.
The other options are not as sensitive as the spot ballistic galvanometer. The elastic galvanometer is a type of galvanometer that uses a spring to measure the current flowing through it. The vibration galvanometer is a type of galvanometer that uses a vibrating reed to measure the current flowing through it. The Duddell galvanometer is a type of galvanometer that uses a rotating coil to measure the current flowing through it.
All of these galvanometers are less sensitive than the spot ballistic galvanometer because they are not as precise. The elastic galvanometer is not as precise because the spring can stretch and contract, which can affect the measurement of the current. The vibration galvanometer is not as precise because the vibrating reed can vibrate at different frequencies, which can affect the measurement of the current. The Duddell galvanometer is not as precise because the rotating coil can rotate at different speeds, which can affect the measurement of the current.