TE Enriched Sample (E)

Lighting 1 32 Chapter Exercise Multiple-choice Questions 1. The graph below shows how human eyes respond to lights of different colours. 400 500 sensitivity wavelength / nm 600 700 Three different monochromatic light sources P , Q and R emit red, green and blue lights, respectively. The sources produce the same luminous flux with the same input power. Which one has the highest efficacy? A. P B. Q C. R D. They have the same efficacy. 2. Initially, an incandescent lamp emits spectrum A (dotted line). After some changes, the lamp emits spectrum B (solid line). intensity 4 8 wavelength / 10 –7 m 10 A B 6 Which of the following statements is/are correct? (1) The lamp becomes dimmer. (2) The pd across the lamp becomes smaller. (3) The luminous efficacy of the lamp becomes higher. A. (1) only B. (3) only C. (1) and (2) only D. (2) and (3) only 3. A 100 W incandescent lamp and a 25 W CFL produce the same luminous flux of 1500 lm. Which of the following statements about them is/are correct? (1) The efficacy of the incandescent lamp is four times that of the CFL. (2) The spectra emitted by them are identical. (3) Both give out different amounts of energy in the form of EM waves per unit time. A. (1) only B. (3) only C. (1) and (2) only D. (2) and (3) only 4. An FTL emits the following spectrum. intensity 400 500 600 wavelength / nm 700 Which of the following is the best explanation for the spectrum produced? A. The phosphor in the FTL does not produce a continuous spectrum. B. The mercury vapour inside the FTL does not produce a continuous spectrum. C. The filament in the FTL does not produce a continuous spectrum. D. The electrons in the FTL do not produce a continuous spectrum. 5. Gas discharge occurs when a current is formed in a gas due to ionization of the gas. Which of the following statements about the gas discharge in an FTL is/are correct? (1) At the start, the pd across the tube has to be larger than 220 V. (2) UV light is produced during this process. (3) Visible light is produced during this process. A. (1) only B. (3) only C. (1) and (2) only D. (2) and (3) only C (1.2) D (1.2) A (1.2) A (1.2) B (1.2) Modified from DSE PP Q3.1 DSE Level-up Companion For more chapter-end questions (mock DSE type), see Level-up Task 81B . Sample © United Prime Educational Publishing (HK) Limited, Pearson Education Asia Limited 2023 All rights reserved; no part of this publication may be reproduced, photocopied, recorded or otherwise, without the prior written permission of the Publishers.