Phy 101 :Electricity And Magnetism Question Paper
Phy 101 :Electricity And Magnetism
Course:Computer Science
Institution: Kenya Methodist University question papers
Exam Year:2010
KENYA METHODIST UNIVERSITY
SCHOOL OF HEALTH SCIENCES
DEPARTMENT OF MEDICAL LABORATORY SCIENCES
PROGRAMME: BACHELOR OF SCIENCE IN MEDICAL LABORATORY SCIENCES
END OF THIRD TRIMESTER EXAMINATION 2010 Academic Year
PAPER: PHY 101 – Electricity And Magnetism
DURATION: 3 HRS
INSTRUCTIONS:
Answer ALL Questions in Section A and TWO in Section B
Write your University ID on ALL scripts
Use only blue, black ball point or ink
SECTION A
Question 1
a) i) State Coulomb`s law (2marks)
ii) Calculate the force between charges +10 -9 C and -4 x 10 -9 C when they are 2 cm
apart in air. Assume E0 = 8.85 x 10 -12 F m -1 (3marks)
b) i) Draw sketches showing the line of force between two positive charges (2marks)
ii) Define potential difference between two points in an electrostatic field and hence define the potential at a point (3marks)
c) i) Define capacitance and give the SI units (2marks) ii) Calculate the combined capacitance of a 4 µF capacity in series with a
parallel arrangement of a 3 and 2 µF capacitor (3marks)
d) i) State Ohm`s law (2marks)
ii) A resistor has a potential difference of 40v when the current in it is 120mA. Find the potential difference across the resistor when the current is 0.6A (3marks)
iii) What length of eureka wire of diameter 0.1mm is required to made a coil of 20sh? (Resistivity of eureka = 4.9 x 10 -7 Om) (3marks)
iv) Give two characteristics of resistors in parallel (2marks)
e) i) Define retentivity as used in magnetism (2marks)
ii) A 40cm conductor is carrying a current of 80A and is situated in a magnetic field of flux density 0.8T. Find the force on the conductor if the angel between the conductor and field is 60°. (3marks)
SECTION B
Question 2
a) i) Derive the force on a current carrying conductor in a magnetic field. Define the symbols used. (5marks)
ii) Use the expression derived in (i) to define the magnitude of the magnetic field.
(2marks)
b) i) Sketch the magnetic field lines for a solenoid. (3marks)
ii) Calculate the magnetic field for a coil consisting of 100 circular loops and carrying a current of 1.0A [ Take µ0 = 4 ? x 10 -7 T m-1] (4marks)
c) Discuss the Hall effect and give its applications (6marks)
Question 3
a) i) State Kirchhoff`s laws and give their significance (4marks)
ii) Use the laws in (i) above to calculate the magnitude and direction of the current flowing through the resistor R3 in the circuit below.
(8marks)
b) i) State Faraday`s laws of electrolysis (2marks)
ii) Give two applications of electrolysis (2marks)
c) Derive the relation R= el/A , where symbols have their usual meaning. (4marks)
Question 4
a) i) Define electric field intensity. (2marks)
ii) Show that the electric field intensity at any point is the negative gradient of the
potential difference (6marks)
b) i) List the factors that determine the ability of a capacitor. (3marks)
ii) Find the equivalent capacitance and charge on each capacitor below
(9marks)
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