In [1]:

```
#Variable declaration
C = 8e-06; # Value of capacitance of capacitor, farad
R = 0.5e+06; # Value of series resistor, ohm
E = 200; # Value of d.c. voltage supply, volt
#Calculations&Results
# Part (a)
tau = C*R; # Time constant of the R-C circuit while charging, s
print "The circuit time constant while charging = %1d s"%tau
# Part (b)
I_0 = E/R; # Initial charging current through capacitor, A
print "The initial charging current through capacitor = %3d micro-ampere"%(I_0/1e-06);
# Part (c)
t = 4; # Time after the supply is connected, s
v_C = 0.632*E; # p.d. across the capacitor 4s after the supply is connected, V
v_R = E - v_C; # p.d. across the resistor 4s after the supply is connected, V
print "The p.d. across resistor and capacitor %d s after the supply is connected = %5.1f V and %4.1f V respectively"%(t, v_C, v_R);
```

In [2]:

```
#Variable declaration
C = 0.5e-06; # Value of capacitance of capacitor, farad
R1 = 220e+03; # Value of series resistor, ohm
R2 = 110e+03; # Value of parallel resistor, ohm
E = 150; # Value of d.c. voltage supply, volt
#Calculations&Results
# Part (a)
tau = C*R1; # Time constant of the R1-C circuit while charging, s
print "The circuit time constant while charging = %4.2f s"%tau
I_0 = E/R1; # Initial charging current through capacitor, A
print "The initial charging current through capacitor = %3d micro-ampere"%(I_0/1e-06)
# Part (b)
tau = C*(R1+R2); # Time constant of the R1-C-R2 circuit while discharging, s
print "The circuit time constant while discharging = %4.2f s"%tau
I_0 = E/(R1 + R2); # Initial discharging current through capacitor, ampere
i = 0.368*I_0; # Discharge current after one time constant, ampere
V_R2 = i*R2; # Potential difference across R2 after one time constant, volt
print "The p.d. across R2 after one time constant while discharging = %4.1f volt"%V_R2
```

In [3]:

```
#Variable declaration
E = 110.; # Value of d.c. voltage supply, volt
L = 1.5; # Inductor value, henry
R = 220; # Value of series resistor, ohm
#Calculations&Results
# Part (a)
di_dt = E/L; # The initial rate of change of current through inductor, H
print "The initial rate of change of current through inductor = %5.2f A/s"%di_dt
# Part (b)
I = E/R; # The final steady current, A
print "The final steady current through inductor = %3.1f A"%I
# Part (c)
tau = L/R; # The time taken for the current to reach its fi nal steady value, s
print "The time taken for the current to reach its final steady value = %4.1f ms"%(5*tau/1e-03);
```