EX-603-A Utilization of Electrical Engineering - Jun 2025 Question Paper

Under each question, How to answer lists the points an answer should cover, outlined by CampusPrep from the syllabus. Check the details against your textbook.

1. 7 Marks
   aState inverse square law and Lamberts cosine law of illumination?
   How to answer

   • State inverse square law: E = I / d^2
   • State Lambert's cosine law: E = (I cos theta) / d^2
   • Explain terms I, d, theta
   • Mention application to illumination calculations
2. 7 Marks
   bIllumination on the working plane of 100 Lux is required in a room $60\,m \times 15\,m$ in size. The lamps are required to be hung $4\,m$ over the workbench. Assuming a suitable space height ratio, a utilization factor of $0.5$ lumens per watt and a candle power deposition of $20\%$ estimate the number rating and deposition of lamps.
   How to answer

   • Calculate area = 60 m x 15 m and required lumens = 100 lux
   • Apply utilization factor 0.5 and depreciation/maintenance factor
   • Estimate total lumens and number of lamps
   • Estimate rating/wattage and disposition using space-height ratio
3. 7 Marks
   aTwo lamps are $20\,m$ apart and are fitted with a $50\,CP$ lamp each at a height of $5\,m$ above ground. Calculate the illumination on the ground

   1. i)Under each lamp
   2. ii)Midway between the lamps
   How to answer

   • Calculate illumination under lamp using E = I/h^2 plus contribution from other lamp
   • Calculate distance and angle for midway point
   • Apply cosine law E = I cos^3 theta / h^2 for each lamp
   • Sum contributions for i) and ii)
4. 7 Marks
   bExplain different methods of energy efficient lighting.
   How to answer

   • Define energy efficient lighting concept
   • Describe methods: LED, CFL, controls, daylighting
   • Mention ballasts, occupancy sensors and dimming
   • State energy saving benefits
5. 7 Marks
   aWrite down the classification of welding methods based on processes.
   How to answer

   • Define welding classification criteria
   • List pressure, fusion, electric resistance, arc, etc.
   • Draw classification chart
   • Give example of each process
6. 7 Marks
   bName the different types of heating methods and describe in detail any one of them.
   How to answer

   • List heating methods: resistance, induction, dielectric, arc, etc.
   • Select one method for detailed description
   • Explain principle, construction and operation
   • Mention applications
7. 7 Marks
   aWrite the advantages of electrical heating. An electric toaster consists of two resistance elements each of $100\,ohms$ calculate the power drawn from $250\,volts$ AC single phase supply when the elements are connected in parallel and second series.
   How to answer

   • List advantages: cleanliness, efficiency, control, safety
   • Calculate equivalent resistance for parallel: 50 ohm and series: 200 ohm
   • Calculate power P = V^2/R for both connections
   • Compare power drawn in two cases
8. 7 Marks
   bA piece of metal having $50\,grams$ in which a golden layer is to be done if the $3\text{-Ampere}$ current is flowing and electrochemical equivalent $0.065$ then in $30\,minutes$ how much weight of gold should be deposited.
   How to answer

   • State Faraday's law: m = Z I t
   • Substitute I=3 A, t=30 min, Z=0.065
   • Calculate weight of gold deposited
   • Mention result in grams
9. 7 Marks
   aDerive the equation for maximum speed by trapezoidal speed time curve.
   How to answer

   • Define trapezoidal speed-time curve parameters alpha, beta, Vm
   • Write distance area relation D = Vm*T - ...
   • Derive expression for Vm in terms of D, alpha, beta
   • State final equation for maximum speed
10. 7 Marks
    bAn electric train has an average speed for $42\,km$ per hour on a level track between the stops $1,400\,m$ apart. It is accelerated at $1.7\,km$ per hour per second and it is braked at $3.3\,km$ per hour per second. Draw the speed time curve for the run and calculate all the parameters.
    How to answer

    • Draw trapezoidal speed-time curve with acceleration and braking slopes
    • Calculate acceleration, braking, running time from average speed
    • Determine Vm, t1, t2, t3
    • List all parameters of the run
11. 7 Marks
    aName different types of electrical braking and explain any one method in detail.
    How to answer

    • List types: plugging, rheostatic, regenerative braking
    • Select one method for detail
    • Explain circuit, operation and energy flow
    • Mention applications and limitations
12. 7 Marks
    bExplain why the DC series motor is suitable for electric traction.
    How to answer

    • State requirements of traction: high starting torque, speed control
    • Explain DC series motor torque-speed characteristics
    • Relate series field to load adaptation
    • Conclude suitability for traction
13. 7 Marks
    aExplain electric vehicle and its components.
    How to answer

    • Define electric vehicle concept
    • List components: battery, motor, controller, charger
    • Explain function of each component
    • Mention block diagram
14. 7 Marks
    bWhat are the characteristics of a good traction system? Justify which motor is suitable for traction system.
    How to answer

    • List characteristics: high torque, overload capacity, efficiency
    • Explain requirement of adhesion, speed control
    • Justify suitable motor type for traction
    • Conclude with DC series / induction motor choice
15. 14 Marks
    Write a short notes (any two)

    1. a)Load equalization
    2. b)Laws of electrolysis
    3. c)Welding transformers
    4. d)Hybrid vehicles
    How to answer

    • Select any two topics from four options
    • Define each with principle and formula/diagram
    • Mention applications
    • Conclude with significance