1.What is the advantage of using square wave-form as an Input Signal? What is the shape of the
outputwhen the input signals are sinusoidal and triangular in shape?
ANS:The square wave simulates a constant cycle of charging and discharging of the capacitor, it makes
it easier to take several measurements and it minimizes error, also, the time constant is clearer in a
square wave when the charging and discharging is complete in the capacitor, which not always the case
in a triangular or sinusoidal wave.
The duty cycle of square wave is 50%, hence, ON and OFF periods are longer compared to sine and
triangle wave. This gives the capacitor enough time to fully charge or discharge. It also enables us
measure the time constant
ii.
The maximum capacitor voltage is equal to peak value of the output waveform. From the oscilloscope
the maximum capacitor is 10 V. Theoretically, the maximum capacitor voltage is equal to the input
voltage.
iii.
Maximum charge of the capacitor can be determined using the formula
Qmax = C*Vmax
= 3.3 nF * 10 V
= 33 nC
iv.
Time constant of the circuit can be determined using the formula
T = R*C
= 10000 * 3.3 * 10 ^-9
= 33 us.
Conclusion:
The capacitor is charged and discharged by the square wave. During the rising edge, the capacitor
charges to its maximum voltage value and during the falling edge the capacitor is discharged. The time
constant of the circuit is 33 us. The time period of the square wave (1/1000 = 1000us) is large enough
and the capacitor will fully charge or discharge before the next cycle begins. It was also observed that
the maximum capacitor voltage is equal to the peak value of the input.