Deflecting torque is a term commonly used in the field of measurement and instrumentation, particularly in the context of instruments like galvanometers, which are used to measure electric currents. Deflecting torque refers to the force that causes the moving element (usually a coil) in the instrument to rotate or deflect from its equilibrium position.
In a galvanometer or similar instrument, there are typically two types of torques at play:
Deflecting Torque: This is the torque that is produced by the interaction between the current passing through the coil and the magnetic field in which the coil is placed. According to Ampere's law, a current-carrying conductor experiences a force when placed in a magnetic field. In a galvanometer, this force causes the coil to rotate, resulting in a deflection of the indicator needle. The greater the current flowing through the coil, the greater the deflecting torque.
Controlling Torque: This torque is generated by a spring or a counterweight mechanism designed to oppose the deflecting torque. The controlling torque is adjustable and is used to calibrate the instrument, ensuring that the deflection of the indicator needle is proportional to the current passing through the coil. By adjusting the controlling torque, the sensitivity of the instrument can be controlled.
The balance between the deflecting torque and the controlling torque determines the position of the indicator needle on the scale of the instrument. When the two torques are equal, the indicator needle comes to rest at a certain angle, which can then be used to measure the magnitude of the current or the quantity being measured.
Overall, deflecting torque is a crucial concept in measurement and instrumentation, as it explains how various types of instruments, such as galvanometers, ammeters, and voltmeters, work to accurately measure electrical quantities. The understanding of these torques allows engineers and scientists to design and calibrate instruments for precise measurements in different applications.