What do you multiply to get electrical energy

Thus, a W incandescent bulb can be replaced by a W CFL, which has the same brightness and color. CFLs have a bent tube inside a globe or a spiral-shaped tube, all connected to a standard screw-in base that fits standard incandescent light sockets.

Original problems with color, flicker, shape, and high initial investment for CFLs have been addressed in recent years. The heat transfer from these CFLs is less, and they last up to 10 times longer. The significance of an investment in such bulbs is addressed in the next example. However, their cost is still high. If the cost of electricity in your area is 12 cents per kWh, what is the total cost capital plus operation of using a W incandescent bulb for hours the lifetime of that bulb if the bulb cost 25 cents?

To find the operating cost, we first find the energy used in kilowatt-hours and then multiply by the cost per kilowatt-hour. The energy used in kilowatt-hours is found by entering the power and time into the expression for energy:. Therefore, it is much cheaper to use the CFLs, even though the initial investment is higher. The increased cost of labor that a business must include for replacing the incandescent bulbs more often has not been figured in here.

Why do incandescent lightbulbs grow dim late in their lives, particularly just before their filaments break? Explain why there is no contradiction here. What is the power of a 1. What power is supplied to the starter motor of a large truck that draws A of current from a A charge of 4. See Figure 2. Figure 2. The strip of solar cells just above the keys of this calculator convert light to electricity to supply its energy needs. How many watts does a flashlight that has 6.

Find the power dissipated in each of these extension cords: a an extension cord having a 0. Electrons in an X-ray tube are accelerated through 1. Calculate the power of the electron beam in this tube if it has a current of An electric water heater consumes 5.

What is the cost of running it for one year if electricity costs See Figure 3. Figure 3. On-demand electric hot water heater. Heat is supplied to water only when needed. What would be the maximum cost of a CFL such that the total cost investment plus operating would be the same for both CFL and incandescent W bulbs? Calculate the cost for hours, as in the cost effectiveness of CFL example.

Some makes of older cars have 6. Alkaline batteries have the advantage of putting out constant voltage until very nearly the end of their life. How long will an alkaline battery rated at 1. A cauterizer, used to stop bleeding in surgery, puts out 2.

The average television is said to be on 6 hours per day. Estimate the yearly cost of electricity to operate million TVs, assuming their power consumption averages W and the cost of electricity averages An old lightbulb draws only By what factor is its diameter reduced, assuming uniform thinning along its length? Neglect any effects caused by temperature differences. Calculate the power loss in a kilometer of such wire when it carries 1.

Cold vaporizers pass a current through water, evaporating it with only a small increase in temperature. One such home device is rated at 3. See Figure 4.

Figure 4. This cold vaporizer passes current directly through water, vaporizing it directly with relatively little temperature increase. In the average electric usage was about a kWh per month b 10, kWh per month c kWh per month d kWh per month. Toggle navigation EDinformatics. Electric Power and Energy Electric Power is the rate at which work is done.

Definition and Equations for Power Electric power, is the rate of doing work, measured in watts, and represented by the letter P. How to calcuate cost of electricity From Con Ed Bill --"We measure yur electricty by how many kilowatt hours kWh you use.

One kWh will light a watt bulb for 10 hours. Delivery kWh System Benefit Change at 0. In the average electric usage was about a kWh per month b 10, kWh per month c kWh per month d kWh per month 3. For example a typical mains lamp uses 60W and a kettle uses about 3kW. You can use the PIV triangle to help you remember these three equations. Use it in the same way as the Ohm's Law triangle :.

The amp is quite large for electronics so we often measure current in milliamps mA and power in milliwatts mW. Normally electric power is useful, making a lamp light or a motor turn for example.