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// A Texbook on POWER SYSTEM ENGINEERING
// A.Chakrabarti, M.L.Soni, P.V.Gupta, U.S.Bhatnagar
// DHANPAT RAI & Co.
// SECOND EDITION
// PART IV : UTILIZATION AND TRACTION
// CHAPTER 4: ILLUMINATION
// EXAMPLE : 4.2 :
// Page number 753
clear ; clc ; close ; // Clear the work space and console
// Given data
lumens = 800.0 // Flux emitted by a lamp(lumens)
cp = 100.0 // cp of a lamp
d = 2.0 // Distance b/w plane surface & lamp(m)
theta_ii = 45.0 // Inclined surface(°)
theta_iii = 90.0 // Parallel rays(°)
// Calculations
// Case(a)
mscp = lumens/(4.0*%pi) // mscp of lamp
// Case(b)
I_i = cp/d**2 // Illumination on the surface when it is normal(lux)
I_ii = cp/d**2*cosd(theta_ii) // Illumination on the surface when it is inclined to 45°(lux)
I_iii = cp/d**2*cosd(theta_iii) // Illumination on the surface when it is parallel to rays(lux)
// Results
disp("PART IV - EXAMPLE : 4.2 : SOLUTION :-")
printf("\nCase(a): mscp of the lamp, mscp = %.f ", mscp)
printf("\nCase(b): Case(i) : Illumination on the surface when it is normal, I = %.f lux", I_i)
printf("\n Case(ii) : Illumination on the surface when it is inclined to 45°, I = %.3f lux", I_ii)
printf("\n Case(iii): Illumination on the surface when it is parallel to rays, I = %.f lux\n", abs(I_iii))
printf("\nNOTE: ERROR: Calculation mistake in case(a) in textbook solution")
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