ES1910
THE UNIVERSITY OF WARWICK
First Year Examinations: Summer 2018
ELECTRICAL AND ELECTRONIC CIRCUITS
Candidates should answer ALL questions.
Time Allowed: 3 hours
Only calculators that conform to the list of models approved by the School of Engineering may
be used in this examination. The Engineering Data Book and standard graph paper will be
provided.
Read carefully the instructions on the answer book and make sure that the particulars required are
entered on each answer book.
,ES1910
1a)
Consider the DC circuit shown in Figure 1a. Using nodal analysis, determine the power
delivered or absorbed by the 20 V source and the power dissipated by the 5 Ω resistance.
Figure 1a
(5 Marks)
1b)
For the DC circuit shown in Figure 1b, use mesh analysis to determine the power delivered by
the 75 V source. Note that the voltage drop across the 5 Ω resistor is given by VX.
Figure 1b.
(5 Marks)
Question 1 continued overleaf
2
, ES1910
Question 1 continued
1c)
For the first order DC circuit shown below, assume that the switch has been in position 1 for
sufficient time so that the circuit is in steady-state. At time t =0, the switch is instantaneously
moved to position 2.
i) Determine the initial capacitor voltage while the switch is in position 1.
ii) Derive the Thevenin equivalent of the circuit seen by the capacitor across the terminals
AB. Use this circuit to determine the steady-state capacitor voltage after the switch is
moved to position 2.
iii) Calculate the time constant of the circuit for t > 0 when the switch is in position 2.
iv) Derive the transient equation of the capacitor voltage VC(t) for t > 0.
v) From the equation derived in (iv), calculate the time taken for the capacitor voltage to fall
to zero.
vi) Derive the capacitor current transient equation for t > 0 when the switch is in position 2.
t
The following equation is useful: VC (t ) VC () (VC (0) VC ())e RC
Figure 1c
(15 Marks)
Total 25 Marks
continued
3
THE UNIVERSITY OF WARWICK
First Year Examinations: Summer 2018
ELECTRICAL AND ELECTRONIC CIRCUITS
Candidates should answer ALL questions.
Time Allowed: 3 hours
Only calculators that conform to the list of models approved by the School of Engineering may
be used in this examination. The Engineering Data Book and standard graph paper will be
provided.
Read carefully the instructions on the answer book and make sure that the particulars required are
entered on each answer book.
,ES1910
1a)
Consider the DC circuit shown in Figure 1a. Using nodal analysis, determine the power
delivered or absorbed by the 20 V source and the power dissipated by the 5 Ω resistance.
Figure 1a
(5 Marks)
1b)
For the DC circuit shown in Figure 1b, use mesh analysis to determine the power delivered by
the 75 V source. Note that the voltage drop across the 5 Ω resistor is given by VX.
Figure 1b.
(5 Marks)
Question 1 continued overleaf
2
, ES1910
Question 1 continued
1c)
For the first order DC circuit shown below, assume that the switch has been in position 1 for
sufficient time so that the circuit is in steady-state. At time t =0, the switch is instantaneously
moved to position 2.
i) Determine the initial capacitor voltage while the switch is in position 1.
ii) Derive the Thevenin equivalent of the circuit seen by the capacitor across the terminals
AB. Use this circuit to determine the steady-state capacitor voltage after the switch is
moved to position 2.
iii) Calculate the time constant of the circuit for t > 0 when the switch is in position 2.
iv) Derive the transient equation of the capacitor voltage VC(t) for t > 0.
v) From the equation derived in (iv), calculate the time taken for the capacitor voltage to fall
to zero.
vi) Derive the capacitor current transient equation for t > 0 when the switch is in position 2.
t
The following equation is useful: VC (t ) VC () (VC (0) VC ())e RC
Figure 1c
(15 Marks)
Total 25 Marks
continued
3
