(a) Discuss the importance of time constant in transient circuit. (b) A RC transient circuit is shown in Figure 1. At time t=0 the switch is closed and the capacitor start to build its potential i. Determine its time constant. ii. Write the mathematical equation for the voltage iii. Write the equations for the current and the voltage iv. If the capacitor is replaced with an inductor of L=10 mH, write the new mathematical equation of voltage across the inductor. R ww 100 ΚΩ +UR- E 20 V Xo T 5.6 µF vc

Question 3 The 555 timer is connected in the following circuit. The resistance of the extra resistor is 102, the capacitance of the extra capacitor is 0.1F. The voltage input at Pin2 is Vcc. What is the output state at Pin3? 1) 2) Decide the voltage input value at Pin 6 when the condition is stable. 3) Decide the output state at Pin3 when a trigger input is applied at Pin2 (voltage input at Pin2 changes from Vcc to 0, and return back to Vcc immediately). 4) After the trigger input is applied at Pin2, how long would the output maintain at the unstable state. Vc R O Output Vo 555 Vc 0.01µF Trigger Input