Phy 310:Electrical Circuits Question Paper
Phy 310:Electrical Circuits
Course:Computer Science
Institution: Kenya Methodist University question papers
Exam Year:2012
END OF 3RD TRIMESTER 2012 (DAY) EXAMINATIONS
FACULTY : SCIENCE & TECHNOLOGY
DEPARTMENT : PURE AND APPLIED SCIENCE
UNIT CODE : PHY 310
UNIT TITLE : Electrical Circuits
TIME : 2 HOURS
INSTRUCTIONS
Answer question One and any other two questions.
Question One
a. Define
i) The coulomb. (2 Marks)
ii) The ohm. (2 Marks)
b. What physical conditions must be maintained for ohm’s law to hold? (2 Marks)
c. Briefly explain the following concepts and state their units (8 Marks)
i. Resistivity.
ii. Conductance.
iii. Conductivity.
iv. Current Density
d. Derive the equation for the equivalent resistance of resistors R1, R2 and R3 in series where the total potential difference is V and the connecting wires have no resistance. (2 Marks)
e. What is the effect of introducing a dielectric in a capacitor? (2 Marks)
f. Giving examples, explain the function of a rectifier. (2 Marks)
Question Two
For the circuit shown below, calculate:
a. The combined resistance of the 12µ and 4.0µ. (4 Marks)
b. The total resistance of the circuit. (2 Marks)
c. Current I. (2 Marks)
d. Voltage V1 (2 Marks)
e. Voltage V2 (2 Marks)
f. Current I1 (2 Marks)
g. Current I2 (2 Marks)
h. Comment on the current I1 and I2. (4 Marks)
I1 12µ
I 2.0µ
• •
4µ
V1 I2
V2
6.0V
Question Three
a. State Kirchhoff’s’ first and second law. (6 Marks)
b. Calculate I1, I2 and I3 in the figure below. (14 Marks)
A
B
I1
I2
F C
I3
4µ
E
D
Question Four
a. State the coulombs’ law and explain permittivity. (4 Marks)
b. What is capacitance and what are its units? (4 Marks)
c. Calculate the changes on the capacitors shown in the figure below and the potential difference across each Y
X 2 mF
• •
Z
3µF
4µF
120V (12 Marks)
Question Five
a. Write down the following abbreviations in full: (5 Marks)
(i) e.m.f
(ii) p.d
(iii) PVC
(iv) µF
(v) LED
b. Calculate the resistance across the terminals T1 – T2 of this network of resistors (6 Marks)
18 µ
• • 47µ
18µ
T1 • • T2
18µ
c. How does a fuse provide protection? (3 Marks)
d. What is the difference between a primary cell and a secondary cell? Give an example of each. (6 Marks)
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