Analysis Given below is a table summarising the parameters of the four lamps. Incandescent Halogen CFL LED Luminous flux 900 900 900 900 (lumen) Power rating (W) 60 43 13 12 Appearance Warm white Warm white Warm white Warm white Dimmable Yes Yes No Yes Life (hours) 1000 2000 12000 25000 Cost $0.60 $2.15 $3.89 $29.99 Energy cost ($/kWh) 0.34 0.34 0.34 0.34 Project Duration (hours) 25000 25000 25000 25000 Area on which the light 3 3 3 3 is incident (m²) 1. As your hypothesis, from the 4 lamps, which one do you think is the most efficient. 2. Calculate the luminous efficacy of each lamp. Then state which one has the best performance. 3. Calculate the illuminance of the lamps. 4. For comparison, take a project duration as 25000 hours, calculate the cost of buying each type of lamp to last for the project duration. 5. Calculate the energy cost of each type of lamp during the project lifetime. 6. Calculate the total cost. 7. Which type of lamp has the least energy cost? 8. Which type of lamp has the least total cost?

Analysis Given below is a table summarising the parameters of the four lamps. Incandescent Halogen CFL LED Luminous flux 900 900 900 900 (lumen) Power rating (W) 60 43 13 12 Appearance Warm white Warm white Warm white Warm white Dimmable Yes Yes No Yes Life (hours) 1000 2000 12000 25000 Cost $0.60 $2.15 $3.89 $29.99 Energy cost ($/kWh) 0.34 0.34 0.34 0.34 Project Duration (hours) 25000 25000 25000 25000 Area on which the light 3 3 3 3 is incident (m²) 1. As your hypothesis, from the 4 lamps, which one do you think is the most efficient. 2. Calculate the luminous efficacy of each lamp. Then state which one has the best performance. 3. Calculate the illuminance of the lamps. 4. For comparison, take a project duration as 25000 hours, calculate the cost of buying each type of lamp to last for the project duration. 5. Calculate the energy cost of each type of lamp during the project lifetime. 6. Calculate the total cost. 7. Which type of lamp has the least energy cost? 8. Which type of lamp has the least total cost?