Exam Paper

KWEKWE POLYTECHNIC
BACHELOR OF TECHNOLOGY DEPARTMENT
BACHELOR OF TECHNOLOGY (HONOURS) IN ELECTRICAL ENGINEERING In Affiliation with

NATIONAL U7NIVERSITY OF SCIENCE AND TECHNOLOGY (NUST)

Course: Electromagnetic Fields 1 Paper Code: EPE 4102

Date: Time:

REQUIREMENTS: 1. Answer book

2. Calculator
INSTRUCTIONS TO CANDIDATES 1. Attempt any five questions out of seven

2. Show clearly all working steps

3. Begin each question on a fresh page.

4. All questions carry equal marks (20 marks)

5. Take permittivity and permeability of free space, ε0= 8.854x 10-12Faradsmetre

μ0=4π x 10-7 Henry/metre

QUESTION 1

a) State Faradays law of electromagnetic induction.
[ 2 marks] b) State Lenz’s Law of electromagnetic induction. [1 mark] c) The field coils of a 6 pole d.c.generator each having 500turns are connected in series. When the series is excited, there is a magnetic flux of 0.02Wb/pole. If the field current is opened in 0.02sec and residual magnetism is 0.002Wb/pole, calculate the average voltage across the terminals .[5 marks]

d) Derive Maxwell’s equation [∇x E=- ∂B∂t] [12 marks]

QUESTION 2\ a) State Maxwell’s four equations for time varying fields in integral form. [4 marks]
Derive the wave equations for E and H in free space from Maxwell’s curl equations.
[ 16 marks]

QUESTION 3 a) Derive the boundary condition tanϑ1tanϑ2= ε1ε2 in electric fields at the boundaries between conductors and dielectrics of different permittivities. Use a sketch for your working. [