In physics, power is the amount of energy transferred or converted per unit time. In the International System of Units, the unit of power is the watt, equal to one joule per second.

When the force makes an angle with the direction of force the component of force along the direction of displacement is taken. If the force is perpendicular to the direction of displacement, work done is zero. When the displacement opposite to the direction of force, work is negative.

Power is the rate at which work is done. It is the work/time ratio. Mathematically, it is computed using the following equation. The standard metric unit of power is the Watt.

Answer : Since, the formula of power is , =Work done / time . It depends upon two physical quantities i.e. Work done and time.

Because power is a measurement of how much work is done in a given time, power can be calculated based on work and time. To find power, divide the amount of work by the time it takes to do the work. Remember that work is measured in joules. Power is often measured in joules of work per second.

The potential energy stored in the electrical field (of the resulting cloud-Earth “capacitor”) is the equivalent of 175,000 MJ. Since a joule equals a watt-second, this would be equivalent to 48.61 megawatt-hours of power IF all the energy could be harvested.

Performance

Since a pulse radar does not radiate continually, the average power is much less than the peak power. In this example, the average power is 1 kilowatt. The average power, rather than the peak power, is the measure of the capability of a radar system.

If you charge capacitor, slowly it will loose its charge due to internal resistance. So capacitor does consume power but practically it is negligible. Ideal capacitor do not consume power.

In inductors and capacitors, the energy supplied by the source is stored in form of magnetic and electric energy respectively. The energy supplied by source in one half cycle to the inductor or capacitor is fed back to source by the component in next half cycle. So inductor or capacitor consume the net power zero.

Power-factor-correction capacitors are used for this purpose. A motor requires inductive or lagging reactive power for magnetizing. Capacitors provide capacitive or leading reactive power that cancels out the lagging reactive power when used for power-factor improvement. The power triangles in Fig.

The energy stored in a capacitor can be expressed in three ways: Ecap=QV2=CV22=Q22C E cap = QV 2 = CV 2 2 = Q 2 2 C , where Q is the charge, V is the voltage, and C is the capacitance of the capacitor. The energy is in joules when the charge is in coulombs, voltage is in volts, and capacitance is in farads.

In an ideal capacitor, zero power is absorbed in a capacitor. In a real capacitor, some power is lost due to the resistance of the wire and metal plates, and some dielectric loss that shows up as heat. This amount depends on the type of dielectric.

A 1-farad capacitor can store one coulomb (coo-lomb) of charge at 1 volt. A coulomb is 6.25e18 (6.25 * 10^18, or 6.25 billion billion) electrons. One amp represents a rate of electron flow of 1 coulomb of electrons per second, so a 1-farad capacitor can hold 1 amp-second of electrons at 1 volt.

It’s just being moved around and stored. An ideal capacitor would not dissipate any power. Real capacitors dissipate a small amount of power whenever current flows through them, due to ohmic losses.

AC Power Waveforms for a Pure Capacitor Therefore, the volt-ampere product gives a negative power as a negative times a positive equals a negative. This negative power indicates that the coil is returning stored electrical energy back to the supply.

As with inductors, the ideal capacitor is a purely reactive device, containing absolutely zero resistive (power dissipative) effects. The source of capacitor loss is usually the dielectric material rather than any wire resistance, as wire length in a capacitor is very minimal.

Naturally, the inductor can be considered as consuming the reactive power from the power source and the capacitor give back (or produces) at the same time. By properly selecting the value of the capacitor we can give back the same quantity of power to the source that consumed by the inductor at the same period.

The gist of a capacitor’s relationship to voltage and current is this: the amount of current through a capacitor depends on both the capacitance and how quickly the voltage is rising or falling. If the voltage across a capacitor swiftly rises, a large positive current will be induced through the capacitor.

In an AC circuit, true power is the actual power consumed by the equipment to do useful work. It is distinguished from apparent power by eliminating the reactive power component that may be present. The true power is measured in watts and signifies the power drawn by the circuit’s resistance to do useful work.

Blenders start at about 200 watts — usually for the stick or personal countertop versions — and can go up to more than 1,000 watts.

Terms in this set (6)

1. Power word equation. Energy transferred (or work done) divided by time taken.
2. Power symbol equation. P = E / t.
3. Power unit. Watt (W)
4. Energy unit. Joule (J)
5. Time unit. second (s)
6. Power definiton. The rate of energy transferred from one form into another.

The toaster has 700 power. How much work can be done in 30 seconds by a 1000-watt microwave oven? 30,000 joules of work can be done. Lamar’s mom has a car with a 182-horsepower engine.

A toaster is found in most kitchens and is a popular home appliance for toasting bread or heating up certain pre-baked toaster pastries. The bread toaster uses from 800 to 1500 watts of energy when in use, an average toaster will use around 1200 watts.

Most TV’s use about 80 to 400 watts, depending on the size and technology. Using a sample cost of 15¢ per kilowatt-hour and five hours of viewing a day, that’s $1.83 to $9.13/mo. ($22 to $110 per year). Below you’ll find energy usage information for different models.

The standby mode electricity estimates range from about 2.25% to 5% of the power consumed while the TV is on. Most TVs today consume less than 5 watts a year in standby, which is a very small amount equal to a few dollars. But that wasted electricity adds up over time.

Here’s a breakdown of the biggest energy use categories in the typical home:

• Air conditioning and heating: 46 percent.
• Water heating: 14 percent.
• Appliances: 13 percent.
• Lighting: 9 percent.
• TV and Media Equipment: 4 percent.

How Much Electricity Do You Save By Unplugging Appliances? For example, unplugging your coffeemaker or microwave is unlikely to make a significant difference, while a computer, modem, and monitor, TV, phone charger, or cable box all consume a considerable amount of electricity even when not in use.

It’s Safer – A Little Bit It actually is safer to unplug your TV at night, but that’snot to say that leaving the TV plugged on and on standby is unsafe.

The conclusion is that turning it off with a “hard switch” at the end of the evening will prolong its life compared to an all-day stand-by. You should leave a modern TV plugged in and on standby mode and not turn off the socket (if switched) or unplug it.

Answer. When you turn off a surge protector — or suppressor, as some people call them — it’s virtually the same as unplugging it; it will save a small amount of energy and is a little safer in a storm than having the surge protector on.

All things plugged in will bleed some energy. Called “standby” electricity loss because it’s so often associated with electronics in standby or idle mode, it’s also known as “phantom” or “vampire” electricity (for obvious reasons). Even turned off, many appliances keep drawing power.

Make it a habit to unplug your computer every night. Not only is this a real energy saver, but it also can protect your computer from serious damage. It’s not an old wives’ tale — a power surge caused by lightning can completely fry your computer.

You should never – Switching off at the socket and pulling the plug out is the only way to be sure no electricity is flowing through an appliance. As well as keeping you safer, switching off and unplugging things at the wall will save you electricity and money!

Common Phantom Energy Appliances

• Set-Top Box. It’s incredibly convenient to record shows automatically in the background, but that means that your PVR is always hard at work in the background.
• Router & Modem.
• Television.
• Blu Ray/DVD Player.
• Computer.
• Cordless Phone.
• Video Game Console.
• Sound System.

Unplugging Items from Overloaded Outlets or Circuits — Fires often start when too many things are plugged into a single outlet or circuit, overloading them. Cords can easily become pinched by furniture and, over time, lead to a fire. Unplugging Appliances by Grasping the Plug — Don’t pull by the cord.

The energy costs of plugged-in appliances can really add up, and unplugging these devices could save your up to $100 to $200 a year. Another benefit of unplugging your appliances is protection from power surges.

It is very important to switch off electrical appliances when not being used because they are mechanical devices that could ultimtely fail, and could case major fires if no one is around to spot the problem or to remove the electrical power socket.

Don’t use water to put it out. Water is a natural conductor of electricity and if you throw water on an electrical fire, you can get shocked or electrocuted. Also, water may enable to fire to spread by conducting electricity throughout the room and potentially igniting flammable materials.

An electrical fire initially has a fairly acrid smell of plastic burning. The short could be in the outlet or in the wiring inside a wall and can be hard to locate. Experts say if you smell something electrical burning you are lucky – most warning signs of electrical fires are invisible and odourless.

Never use water to put out an electrical fire. Water is a natural conductor of electricity. This means that you can easily shock yourself if you use water to try and put out an electrical fire. Water can potentially make the fire worse as the element will turn the splashed area into an electrical hazard.

No. Flour should NEVER be used to extinguish a grease fire. It could be ignited, making matters worse. Baking powder and baking soda are NOT the same thing, and like flour, will make a fire worse.

Yes, theoretically, salt would put out an electrical fire, but only IF you had enough salt on hand to completely smother the fire and put it out by cutting off the oxygen supply. To put out a fire, you need to take away either heat, oxygen or fuel.