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S210 11/02/
THE MANCHESTER METROPOLITAN UNIVERSITY
FACULTY OF SCIENCE AND ENGINEERING
DEPARTMENT OF ENGINEERING AND TECHNOLOGY
SESSION 2003/
Examination for the HND ELECTRONIC ENGINEERING YEAR ONE
UNIT 64EE1201 : ELECTRICAL ENGINEERING SCIENCE I
Wednesday 2 June 2004
2.00 pm to 4.00 pm
Instructions to Candidates
Attempt ALL questions.
Assessment will be based on the marks obtained from your best two attempts.
Breakdown of marks for each question is shown in square parentheses.
All questions carry equal marks.
Any type of calculator may be used, but those with non-volatile memory storage facilities must be seen by an invigilator and shown to have been reset immediately before the commencement of the examination.
04/10/2004 continued
- In the circuit of Figure Q1, explain the purpose of the diode. [2]
The circuit initially has no current and the switch is closed at time t = 0. Calculate:-
(a) the circuit time constant when the switch is closed. [2]
(b) the current iL when the switch has been closed for 1 second. [2]
(c) the current iL 2 ms after the switch was closed. [4]
(d) the voltages v (^) L, and v (^) R2 2 ms after the switch was closed. [4]
(e) the time taken for the current iL to reach 25 mA. [4]
The switch is kept closed for 1 second and then opened.
Calculate:-
(f) the circuit time constant when the switch is open. [2]
(g) the time taken for the current iL to fall to 20 mA. [3]
(h) the voltage v (^) L at this time (indicate also its direction). [2]
You may assume that the equations relating the growth and decay of current in a series connected resistor and inductor are:
where the symbols have their usual meanings
Figure Q
i = I (1o − e ) i = I (^) oe
− Rt − L
Rt and L
R
1 =82^ Ω
t=
G (^) 600mH
i
30V v (^) L
v (^) R
R 2 =118 Ω L
i (^) s
Vs
S210 11/02/
- State and explain:
(a) The Maximum Power Transfer Theorem for an a.c. circuit and; [4] (b) Thevenin's Theorem. [4] (c) For the circuit of Figure Q3, it is required that maximum power is transferred from the source to the load impedance Z. All stated impedances are for a frequency of 1 kHz. Calculate:
(i) the component values of Z for maximum power dissipation in Z and; [12] (ii) the value of this maximum power dissipation. [5]
Figure Q
END
G Z
(5+j12)Ω
20/0 (3-j4)Ω
0 V
1kHz
