Efficiency
· What two things does efficiency compare?
· Write down the formula for efficiency.
· What is efficiency measured in?
· Can it ever be equal to, or more than 100%? Give a reason for this.
· Calculate the efficiency of a bulb if Energy in = 100 J and Useful energy out = 10J
· An equivalent energy saving bulb gives off the same amount of light (100W) but “uses” 25 W of electricity. Calculate its efficiency
· Calculate the efficiency of a car if Energy in = 5000 J and Energy out = 1250 J
