Efficiency

Ratio of useful energy output to the energy input Ex: Incandescent Light Bulb ▫5% of energy used is useful (Light) ▫95% of energy is wasted as heat ▫  5% efficient

Efficiencies Candle – 0.04% 100W Incandescent – 2.6% Projection bulb incandescent – 5.1% Fluorescent Bulb – 11-15% Light Emitting Diode (LED) – 12%

Phasing Out Incandescent Bulbs Europe, Canada, US and many other countries have started to phase out incandescent light bulbs due to their inefficiency

Where: E out – Useful energy output E in – Energy input

Where: P out – Useful power output P in – Power input

Example 1: Your car’s engine takes in 10,000J of energy per second. The energy output measured in the car’s motion forward is 1,600J per second of kinetic energy. What is the efficiency of the car?

Power – Pg 175 # 1,2,4,5 Efficiency - Pg 182 # 1-4

Overall Efficiency Used to calculate the accumulated efficiency of a process

Become a Vegetarian Each step up the food chain is about 10% efficient So if cows need to eat 100,000J of plant energy to grow and live, humans only get 10,000J of that energy So one vegetarian is equivalent to 10 meat eaters

Ex 2: 100J of energy is produced by Niagara Falls. Long distance power lines are 99.5% efficient, local power lines are 99% efficient, if you use: a)Incandescent bulbs (5.1% efficient), how much useful energy do you receive? b)Fluorescent bulbs (12% efficient), how much energy do you you receive?

Pg 194 # 1 Pg 195 # 2-4 Read 197 and make notes on ways to generate electricity more efficiently