Power and Efficiency

Efficiency is calculated by useful energy output divided by total energy input, expressed as a percentage

• False

• True

A kettle uses 100J of electrical energy to produce 7J of sound energy and 93J of thermal energy. How efficient is the kettle?

• 100%

• 7%

• 93%

• 95%

A washing machine uses 250J of electrical energy to produce 125J of useful energy. How efficient is it?

• 5%

• 50%

• 55%

• 100%

Tags

NGSS.MS-PS3-5

• 100%

• 80%

• 40%

• 10%

Tags

NGSS.MS-PS3-3

Which of the following is an example of energy efficiency?

• A light bulb that converts 90% of electrical energy into light

• A car engine that converts 30% of fuel energy into motion

• A heater that converts 50% of electrical energy into heat

• A solar panel that converts 20% of sunlight into electricity

Tags

NGSS.MS-ETS1-2

the percentage of energy put into a system that does useful work.

• Energy Conservation

• Energy Efficiency

• Energy Wattage

• Electricity

Tags

NGSS.HS-ETS1-3

Efficiency is a measure of

• how much work is done per second

• how much work is output versus to how much work is input

• how much power is used per second

• how much power is output versus how much power is input

Tags

NGSS.HS-PS3-3

Which among the following is the most energy-efficient?

• • Incandescent bulb

• • Fluorescent tube light

• • Compact fluorescent lamp

• • All are equally efficient.

Which among the following is the most energy-efficient?

• • Incandescent bulb

• • Fluorescent tube light

• • Compact fluorescent lamp

• • All are equally efficient.

Tags

NGSS.MS-ETS1-2

The percent of energy that is used for work

• Energy efficiency

• Renewable energy

• Nonrenewable energy

• Combustion

Tags

NGSS.MS-PS3-5