Top Answer
User Avatar
Wiki User
Answered 2009-10-02 09:38:17

Take the wattage of the light times the length of time in hours that the light is left on. Divide this figure by 1000 to get kilowatt hours, multiply that figure by the cost of electricity in your area in cents per kilowatt hour. The final figure will give you the cost of operating the light or wasted electricity if no one benefiting from the light.

For more information see the answer to the Related Question shown below.

User Avatar

Your Answer


Still Have Questions?

Related Questions

How much energy is wasted from leaving the lights on?

A lot

How much energy is wasted by leaving an appliance on standby?

Leaving an appliance on standby means it is using 40% of the energy it would if it was actually running.

Would heat or light in a light bulb is wasted energy?

Lightbulbs are meant to produce light but they also produce heat energy that is wasted. This depends on the efficiency. A light bulb that is more effecient wouldn't waste as much energy on heat as a less effecient lightbulb.

What is the wasted energy from a light bulb?

That refers to the electrical energy that is converted to heat. For some purposes this may be desirable, but usually this is waste energy. In an old-fashioned incandescent light bulb, perhaps 5% of the electrical energy is converted to light, the remainder is wasted. Newer light bulbs (fluorescent light bulbs, and even more so LED lamps) are much more efficient.

How does fluorescent light bulbs help conserve energy?

It's because it need only 20% of the electrical power to produce as much light, therefore less energy is wasted.

Most energy transformations produce what form of energy?

In most energy transformations, part of the energy is wasted. Much of the wasted energy is usually converted to heat.

How much energy input is wasted at the power stations?

2/3 of energy input is wasted at the power station.

How much energy is wasted by a microwave?


Why is an incadescent bulb a very inefficient light source?

An incandescent light bulb is very inefficient light source because of the amount of heat energy wasted when it is energized.

How much energy is wasted at school?

A lot of energy can be wasted at schools. Sometimes, central heating is left on in rooms with no one in them.

How much energy does leaving a light on use?

100%! dont leave lights on for ever!To answer the question (!)...Multiply the power-rating of the lamp, converted to kilowatts, by the length of time it is on, converted to hours. This tells you how much energy has been wasted, in kilowatt hours. You then need to find out the cost per kilowatt hour charged by your utility.

What is the rule for working out how much electricity you are wasting?

Energy input minus useful energy output. So if you were using a lamp you could work out how much energy was going in and how much was actually coming out in light. Then whatever's leftover is being wasted.

How much blood and energy is wasted when we release sperm?

Blood? Wasted? Wow! My whole perspective has changed!

What form does machines wasted energy take?

Usually, much of the wasted energy takes the form of heat energy. However, part of the energy can also be in other forms, for example sound.

How much water is wasted every minute?

There are hundreds of gallons of water wasted every minute. Water is wasted by leaving the faucet running, taking long showers, and flushing toilets when unnecessary.

How are light emitting diodes able to produce so much light but without producing any heat?

The electrons in the electric circuit excite the atoms of the diode efficiently, not much energy is wasted (in the form of heat).

How does incandescent light bulbs affect global warming?

In a incandescent light bulb almost 90% of the energy taken in is being wasted as heat. only 10% is being used as visible light. this means that alot of energy taken in from ex sun,vind and water are not being used as it should have been. Thats why the LED bulbs are so good because they dont give out as much wasted energy

How is nuclear energy wasted at home?

The only nuclear energy we use in the home is through electricity, a proportion of which is produced by nuclear plants. So it amounts to how much electricity you waste, for example leaving lights on in unoccupied rooms, unnecessary heating or cooling, leaving your computer on 24/7, and so on.

How much energy is wasted if the light bulb is 5 percent efficient?

It is not quite as straight forward as saying 95%. All energy going through the light bulb is being used in one form or another. If the room needs heat, the bulb is assisting in this heating. We use light bulbs like this for incubators or to keep pump rooms from freezing in the winter (two examples). In both of those cases, the light is really the only wasted portion of the energy consumed. If we are discussing only the light portion of the bulb. 95% of the energy goes to non visible light consumption.

How much energy is wasted today?

Well it all depends on how youy look at it

How much energy is wasted on Christmas lights?

The power is specific to the lamp set.

What are Sankey diagrams used for?

They are used to show how much energy is used and how much is wasted in an object/item.

What is useful and wasted energy?

Useful energy is energy that can be converted to any other type of energy. Wasted energy is no longer available to be converted - usually because it got spread out too much, or because it got converted to heat. Heat can be partially, but not completely, converted to other types of energy.

How much electricity is wasted?

the number of electricity wasted is wasted

Why are jet packs rubbish?

Too much wasted energy for too little practical use.