ES191 - Electronics and Circuits - Exam Questions and Mark Scheme 2019 - University of Warwick

ES1910


THE UNIVERSITY OF WARWICK


First Year Examinations: Summer 2019


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 below in Figure Q1a. Assume that the circuit is in steady state
while the switch is in position A.

i) Derive the Norton equivalent circuit seen by the 3 H inductor and hence calculate the
initial inductor current while the switch is in position A.

ii) At time t = 0, the switch is instantaneously moved to position B. Calculate the steady-
state inductor current after the switch is moved to position B.

iii) Calculate the time constant of the circuit seen by the inductor while the switch is in
position B.

iv) Derive the equation for the transient response of the inductor after the switch is moved.
The following equation is useful:

Rt

iL (t )  iL ()  (iL (0)  iL ())e L



v) Calculate the inductor voltage 4 s after the switch is moved.




Figure Q1a
(15 Marks)




Question 1 Continued overleaf…



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, ES1910

1b)
For the DC circuit shown below in Figure Q1b, use mesh (loop) analysis to determine the power
dissipated by the 20 Ω resistor.




Figure Q1b.
(5 Marks)
1c)
For the DC circuit shown below in Figure Q1c, use nodal analysis to calculate the power
delivered by the 25 A current source.




Figure Q1c.
(5 Marks)
(Total 25 Marks)




_______________________________________________________________________________

Continued…


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