Why some countries in the world use 220 volts 50 Hz while some 115 volts 60 Hz? e.g. India use former and USA us later for home electricity why there is no universal standardization for it?
121907
They developed appliances with different needs.\nBut they should standardize.  Tell me, which country do you tell to change their ENTIRE power grid structure?
317519
if you live in the US\n110V for most appliances\n220v/110v for bigger ones\nif you live over in Europe \n220V
165602
400 Hz transformers, motors and generators are always smaller and lighter than their 60 Hz equivalents. The motors and generators use lower-inductance windings and tend to operate at higher rpms and lower torques. However, according to the ref., this weight savings comes at the cost of lower efficiency due to greater wiring inductive loss at higher frequency.
574821
look on the back, by your power plug. there should be a little (usually red) switch, and it should say 110 volts (or is it 115? i'm sorry, i can't read the thing on my computer because it is partially covered. oh well, it's 1-1-something!) anyhow, sometimes this switch gets flipped to 200-something (220/240?) this voltage can cause odd behaviour and also damage your computer (be careful, data loss is possible!!!) if it is switched to the wrong voltage. the 110 is for US use (i am assuming youa re in the US) so make sure it's set to that. good luck! =D
29459
no that is why our electricity is ran house to house in ac.  it is safer to operate ac and also more energy efficient.
51178
Volts is not a measure of power. It is a measure of potential energy. To measure power you should be thinking watts. So a 100W lightbulb is twice as powerful as a 50W lightbulb (W stands for Watts).\n\nNow suppose you have a 100W bulb at 100 volts (100V). It must be consuming 1 Ampere (1A) of current because Watts = Volts x Amperes. But a 100W bulb at 10V would draw 10A (10x10). It would be wrong to say that the 10V bulb is less powerful than the 100V bulb if they were both 100W.\n\nThat being said, real light bulbs are rated in watts at their operating voltage. So a 100W bulb at 110V draws about 1A, but if you put 12V through it, it would not draw enough current to be a 100W bulb anymore. In other words, don't think that because a 100W bulb is marked 100W that it always draws 100W under any circumstances -- it is just a convinient marking to guage relative strength.
520775
Not necessarily! \n\nOutput is usually measured in watts at the speaker connections, not volts.\n\nThe Line-out "standard" is 1v peak-to-peak on most systems except those designed to drive many speakers, (like restaurant background music), which are usually either 75v or 150v to avoid "line loss" in large systems with long runs, which then use special transformers at each speaker to convert back for the speakers.
585192
AC & DC of the same voltage can push the same amount of current through a wire.  In regular use however, we never see them at the same voltage.  There is no DC power transmission, and no one makes AC batteries.\n\nYour portable stereo either has an adapter to lower the 120VAC house voltage & convert it to DC, or has circuitry to raise your 12VDC car voltage & convert it to AC.  The former is more likely.  Since homes have 120VAC power, most appliances that use lower voltage DC have adapters, either built-in or external.
227185
We in the USA never unplug things.\nWe have a great many things in every room of our houses and they always stay plugged in all the time.\n\nI can look right now at three lamps plugged in, about 20 pieces of computer equipment all plugged in, a huge TV, a DVD player, A VCR, and an electric piano, that all stay plugged in all the time.
74298
Here are some sites that may help.  Both have circuit examples utilizing LVDT's.  Hope this helps.
677011
Kilowatt\nCost depends on method of generation and location
552377
Celsius is the world meteorological standard.  Kelvins are the scientific standard.  Fahrenheit is a non-standard and archaic unit used by Americans only.
61802
This depends on the logic family employed. For "standard CMOS" which is common today, +5V is 1 and 0V or ground is 0. However, other systems use other voltages. Lower voltages are common today for a few reasons. 3.3V logic, for example, is widely used where 3.3V is a 1 (and 0V is 0). However, it is possible to have negative logic. In addition, some high speed systems like ECL use voltages like -1.75V for a 0 and -0.9V for a 1 (this allows transistors to stay out of saturation which makes for fast switching but poor noise immunity and difficult design).
536943
You will need an adapter.\nhttp://en.wikipedia.org/wiki/List_of_countries_with_mains_power_plugs,_voltages_and_frequencies
318058
They are not proportional.  Watts are units of power, volts are not.  Similarly, you can't ask "how many kilometres per hour are in a kilogram?"\n\nIn direct current conditions, the power expended in a device (in Watts) is equal to the voltage across the device (in Volts) times the current passing through the device (in Amperes).
662971
Types of transformers\nIn general, transformers are used for two purposes: signal matching and power supplies.\n\n \n\nPower Transformers\nPower transformers are used to convert from one voltage to another, at significant power levels.\n\n \n\nStep-up transformers\nA "step-up transformer" allows a device that requires a high voltage power supply to operate from a lower voltage source. The transformer takes in the low voltage at a high current and puts out the high voltage at a low current.\n\nExamples:\n\n    * You are a Swiss visiting the U.S.A., and want to operate your 220VAC shaver off of the available 110 VAC.\n    * The CRT display tube of your computer monitor requires thousands of volts, but must run off of 110 VAC from the wall. \n\n \n\nStep-down transformers\nA "step-down transformer" allows a device that requires a low voltage power supply to operate from a higher voltage. The transformer takes in the high voltage at a low current and puts out a low voltage at a high current.\n\nExamples:\n\n    * Your Mailbu-brand landscape lights run on 12VAC, but you plug them into the 110 VAC line.\n    * Your doorbell doesn't need batteries. It runs on 110 VAC, converted to 12VAC. \n\nThis page from the All Electronics catalog (#103, Winter 2003) shows some step-down transformers.\n\nIn many cases, step-down transformers take the form of wall warts.\n\n \n\nIsolation transformers\nAn "isolation transformer" does not raise or lower a voltage; whatever voltage comes in is what goes out. An isolation transformer prevents current from flowing directly from one side to the other. This usually serves as a safety device to prevent electrocution.\n\n \n\nVariable auto-transformers\nA "variable auto-transformer" (variac) can act like a step-up transformer or step-down transformer. It has a big knob on top that allows you to dial in whatever output voltage you want.\n\nThis page from the All Electronics catalog (#103, Winter 2003) shows some variacs.\n\nWARNING: A variable auto-transformer does not provide isolation from line current. For that you need an isolation transformer.\n\n \n\nInverters\nAn "inverter" takes a DC power source and boosts it up to a higher voltage. The most common type of inverter takes power from an automobile and cranks out 110 VAC to run appliances and power tools. Inverters are also used to operate fluorescent lamps from battery power.\n\nTechnically, an inverter isn't a transformer; it contains a transformer (and lots of other stuff).\n\n \n\nSignal Transformers\n"Signal transformers" also take one thing in and transform it to another thing out. But in this case, the power levels are low, and the transformed thing carries some type of information signal.\n\nIn most cases, these transformers are thought of as impedance matching.
474107
http://froogle.google.com/froogle?q=220+volt+,+20Kw+generator&hl=en&lr=&safe=off&sa=X&oi=froogle&ct=title