Year 7 Science · Unit 3 · Lesson 13
Apply Worksheet
Learning Goals
Real-world context
The Sydney Olympic Park Velodrome in Sydney hosts major cycling events and requires powerful overhead lighting. In 2018, venue managers compared three lighting options: incandescent bulbs (~5% efficient), fluorescent tubes (~22% efficient), and LED panels (~88% efficient). All three options delivered the same useful light output of 50 000 J per second to illuminate the track.
(a) The venue uses 50 000 J per second of useful light. Calculate the total energy input per second needed for each lighting option. Show your working for at least two options.
(b) Predict which lighting option would produce the most noticeable heat in the velodrome. Explain what happens to the "wasted" energy using your knowledge of energy transformation.
Read the graph
Study the bar chart showing approximate efficiency values for five Australian power sources. Then answer the questions below.
Data: Australian Energy Regulator, CSIRO GenCost 2023–24
(a) Which power source has the highest efficiency? By approximately how many percentage points does it exceed the second-most efficient source shown?
(b) A coal power station produces 1 000 J of electrical energy. Using the graph, estimate how much of the original chemical energy in the coal was wasted. Where does this wasted energy go?
(c) Solar panels have a lower efficiency than coal. Explain why Australia still invests heavily in solar energy despite this lower efficiency percentage.
Wrap Up
In one sentence, what was the main idea of this lesson?