[SOLVED] Voltage and Current Relation

[tahir4awan]

Voltage and current are define by simple relation V = IR. At lower dc voltages it is clearly understood. But when it comes to AC it is confusing. First of all I don't know the purpose of choosing 220v or 120v. If 120v is working fine then why using 220v.
If the purpose of voltage is only to drive electrons i.e current then, for example if a device operate at 1 amperes with 220volts is it possible that the device will work with 60v and 1 amperes of current which is the operating current of device.

 

[FvM]

The standards for domestic power supply have technical as well as historical reasons. Mains electricity - Wikipedia, the free encyclopedia
Technically, the purpose of providing power supply to household and industry in a range of a few W to several 10 kW per load sets a reasonable voltage range.

Some basic mathematical relations of AC power supply are addressed in this article Alternating current - Wikipedia, the free encyclopedia

 

[keith1200rs]

I don't understand your question. Ohms law applies to AC and DC voltages. I am not sure where you "choose" 120V or 220V AC - it is your electricity supply voltage so that is what you have to use. I think you must have a particular problem or application in mind so you must give more details or a specific example.

Keith

 

[alexan_e]

if a device operate at 1 amperes with 220volts is it possible that the device will work with 60v and 1 amperes of current which is the operating current of device.

Since you put your question in a theoretical form i would have to say no, the device will not work.
The first device uses 220v 1A -> P=V*I so 220W
The second device 60v 1 amp -> 60W (suppose it was modifier to work with 60v and still draw 1A)

To have the same result you would have to design the second device to work with 60v 3,67A to have the same watts as the first device.
If for example this was a hairdryer (suppose it is a very small one) in the first case the air would be very hot while in the second with only 60W it would be fairly cold.
It would be the same with a fan (air blower), the speed and amount of air in 60v would be very little compared to the 220v.

Alex