1. A roof receives 1,000 W/m² of energy from the Sun on a clear, sunny day. How many watts would be produced from a 5cm wide by 20cm long solar cell positioned on the roof if the efficiency of the solar cell is 14%?

2. A roof receives 1,000 W/m² of energy from the Sun on a clear, sunny day. How many watts would be produced from a 5cm wide by 20cm long solar cell positioned on the roof if the efficiency of the solar cell is 14%?

3. A houseowner replaces their filament light bulbs with LED lighting. This is 85% efficient and requires only a 7 watt input. What is the useful power output of the new lights?

4. How is the efficiency of an energy transfer expressed?

5. If a filament light bulb consumes 150 J/s and produces 12 J/s of light energy, what is its efficiency?

6. If a filament light bulb consumes 150 J/s and produces 12 J/s of light energy, what is its efficiency?

7. As a train travels along its rails, its wheels create sparks. Apart from this light energy, what other forms of energy are wasted?

8. When the outside temperature is cold, the air inside a car is warmed by some of the thermal energy from the engine. What effect does this have on the overall efficiency of the car engine?

9. Distributing electrical energy through the 400,000 V cables of the National Grid wastes some of the energy of the electricity (see below). What is the efficiency of this part of the system to the nearest whole number? Total power generated: 62,161.5 MW
Step-up transformer losses: 157 MW
Step-down transformer losses: 142 MW
Losses caused by heating of the cables during transmission: 1.4%

10. What is a Sankey diagram?