EE102 Fundametals for Electrical and Electronics Engineering
Short Test I 2020-Solution
Duration: 50 Minutes
Surname __________________ Other Names: ______________________
1.
Weighting: 7.5%
ID #: _________________________
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a. A charge q = 6.5 µC moving with a velocity of v  3 ˆi  5 ˆj  2 kˆ m s-1 in a region in

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which the magnetic field is B  2 ˆi  3 ˆj  4 kˆ T. Find the magnetic force vector, F on
this charge.
(3 marks)
Solution:
b. Explain Faradays Law and state three ways to change magnetic flux.
(4 marks)
Solution:
The electromotive force induced in a circuit by variation of the magnetic flux.
1) change B (increase or decrease magnitude of magnetic field)
2) change A (by altering shape of the loop)
3) change the angle between B and the area vector A
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c. Two point charges attract each other with an electric force of magnitude F. If the
charge on one of the particles is reduced to one-third its original value and the
distance between the particles is doubled, what is the resulting magnitude of the
electric force between them?
(3 Marks)
Solution:
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2. For the circuit given below, determine i1 to i5
(10 marks)
Solution
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3. For the circuit in figure below, find the value of io using
a. Mesh analysis.
b. Nodal analysis.
(10 marks)
(10 marks)
io
12 V
12 Ω
8Ω
+ -
5Ω
+
vx
_
6A
5vx
Solution:
(a)
supernode
io
v1
5Ω
+
vx
12 V
+
KCL for the supernode :
12 Ω
v2
8Ω
6A
v3
v1
 6  5vx  0 v x  v1  v1  1.25 V
5
5vx
v2  v1  12  13.25 V
KCL for node 3 :
5v x 
v3  v2 v3  v1
122v1  3v2
v v

 0  v3 
 38.45 V i0  1 3  3.1 A
8
12
5
12
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(b)
io
12 Ω
KVL eqn. can be written only for mesh 1:
i1
12 V
+
8Ω
5Ω
+
vx
5vx
i2
6A
i3
12  12i1  8(i1  i3 )  0
(1)
i3  5v x  5( 5i2 )  25i2
i3  i2  6 A
 i2  0.25 A
Substitute in (1)
 i3  6.25 A
 i1  i0  3.1 A
****End of Questions****
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