Answer Happy

1. Two sensors are mounted on a half-white rotating disk as shown below. Sensor output is 5V for white and ov for dark. Specify the digital element or elements to put in the black box so that the LED is ON for clockwise rotation. (Hint: Look at the waveforms and include D flip-flops only.) 2. At the instant the switch of figure 2 is closed, the voltage on the capacitor is 0 volts. The resistance of R is 30 K2 and Voc = 12 volts. Sketch vo versus time. How long does it take to saturate the op amp? C=0.25 F 3. Determine the resistance of a bar of n-type silicon at room temperature(300°K). The length of the bar is 10 cm and its radius is 20 mm. Silicon: Mn = 0.135 m2/V-sec, Hp = 0.048 m2/V-sec, n; = 1.5 x1010 /cm3, atomic weight = 28.09, density = 2.33 x 106 g/m3, T = 300°K. Np = 5 x1020 As atoms/m3 Hint: Convert cm units to m units in the intrinsic carrier density n; given above. 0.25 F +5V 76 t- Black Box + to**-Voc with B Vo Suka " with Fig. 2