X=4

Question 2 (Total 20 marks) (X = 4 for odd no. in the last digit of student ID; X = 8 for zero or even no. in the last digit of student ID) A 150-W metal halide lamp emits the following spectrum of radiant power: 8.6 W at 450 - 500 nm; 1X.0 W at 500 - 550 nm; and 18.4 W at 550 - 600 nm. It is housed in an opal spherical diffuser with a radius of 15 cm. The light output ratio of the diffuser is 0.7X. The diffuser is placed at 3 m vertically above the centre of a circular table with a diameter of 2 m. The spectral efficiency for photopic vision is given by V(2) = sin"[(1 - 380)/350], where 2 is in nm. The maximum luminous efficacy is taken to be 683 Im/W at 555 nm. (a) Evaluate the luminous efficacy of the diffuser. (b) Find the luminous intensity of the diffuser. (c) Calculate the luminance of the diffuser. (d) Find the MAXIMUM and MINIMUM horizontal illuminances on the table