Question: An external magnetic field B = 1 T interacts with a sinusoidal current of unknown amplitude and rotates the rigid plate shown in Figure by an angle i. Optical detection with an incident beam at a0 = 20° and a capture screen at a distance h = 200 nm from the micro device plane indicates a maximum deflection of the reflected beam of d = 50 nm (see Figure). The three identical flexible members have a circular cross-section of diameter dr = 2 nm, their length is l = 300 nm, while their material modulii are E = 140 GPA and G = 112 GPa. The rigid plate is defined by r = 80 nm, a thickness hp = 8 nm, and a mass density t = 6000 kg/m3 . Knowing that the current's frequency is one half the natural rotary frequency of the mechanical microsystem in the i direction, determine the current amplitude.
