# Feedback Comments on Electricity

by Ron Kurtus

A total of 724 comments and questions have been sent in. They are listed according to date.

You can read them to further your understanding of the subject.

## List of next 10 letters

### Country

Electrical Power How does power stuff work? USA

AC World Voltages Why aren't higher AC frequencies used? Malaysia

DC What does 750mA convert to amps? USA

AC Transformers Application of magnetism in a transformer Zambia

AC Wiring Basic electrical supply in India India

Electric Charge Sending electrical surge through email Canada

AC What is an eddy current? Pakistan

AC Do AC electrons travel great distances? Malaysia

AC World Voltages Questioning information on frequencies Germany

AC World Voltages Wants to use a 240 volt generator in Bali Australia

Next 10

First 10 letters

## How does power stuff work?

Topic: Electrical Power

### Question

May 28, 2015

Hello, I found your post online and had a few questions. I am wondering how all this power stuff works. If i had a device that as it is measured shows 100W does that mean the device is currently drawing 100W or is it going to draw 100W over 1 hour? Does that mean that it will draw 2400W over 24hrs? Thank you, ~Ernie

Ernie - USA

26035

Wattage is the electric power or energy expended per unit time.

The amount of electric power used is the wattage multiplied by the time used. The unit of power is usually kilowatt-hour.

A 100W light bulb used for 24 hours will draw 2400 watt-hours or 2.4 kw-hr of power.

## Why aren't higher AC frequencies used?

Topic: AC World Voltages

### Question

May 11, 2015

Hi, i would like to know that ignoring all the historical stories or incidents why 50Hz and 60Hz were being used for AC supply, what are the reasons 50 and 60 Hz are being used? Why not 100Hz?

Is it regarding to the efficiency of the electrical appliances, and how 50 and 60Hz different in terms of cable transmission.

Thank you very much!

Gary - Malaysia

25990

AC frequency varied from 25Hz to higher, according to the speed of the turbine and generators creating the current. The standards of 50Hz and 60Hz were selected by convenience, although neither is really more effective than the other.

100Hz could have also been selected, but it is too late to change all the equipment using the other frequencies.

Power frequencies as high as 400 Hz are used in aircraft, submarines, and military equipment. Such high frequencies cannot be economically transmitted long distances; the increased frequency greatly increases impedance, making power transmission difficult. Thus, 400 Hz power systems are usually confined to a building or vehicle.

## What does 750mA convert to amps?

Topic: DC

### Question

April 21, 2015

What does 750mA convert to amps?

Jon - USA

25939

mA means miliamps. "mili" is 1/1000, so 750mA = 0.75A.

## Application of magnetism in a transformer

Topic: AC Transformers

### Question

April 16, 2015

most of electrical equipment depends directly or indirectly on magnetism. without magnetism the electrical world we would perceive today would not exist (a)Explain the application on magnetism in a transformer with an aid of a simple diagram

fulko - Zambia

25924

Magnetism and electricity are connected through electromagnetic waves. They do not exist independently. Magnetic fields create electric fields and electric fields create magnetic fields.

Thus, the movement of electrons in wires in one part of the transformer creates a magnetic field that creates movement of electrons in the other end of the transformer. The voltage of the electricity depends on the ration of the windings of thw wire.

## Basic electrical supply in India

Topic: AC Wiring

### Question

April 4, 2015

what is the basic supply does a house require......? is it a 240 volts or watts

neevan - India

25889

AC electricity in India is 240 volts at 50 Hz.

Watts equals the voltage times the current and it related to the resistance of the circuit.

## Sending electrical surge through email

Topic: Electric Charge

### Question

January 27, 2015

Can an electric charge/pulse/surge be sent from one computer to another by email. If so, how? Peter

25727

Email consists of text and pictures. Electrical pulses cannot be sent through email.

However, a spark or electrical surge from one computer that is shorted out, could affect the electronics in another computer. Likewise, surges from lightning can effect the electronics. That is why a surge protector is often used in the power connection.

## What is an eddy current?

Topic: AC

### Question

January 5, 2015

What is Aidy current?

Faisal - Pakistan

25684

I assume you mean an eddy current, which is a circular electric current induced within conductors by a changing magnetic field in the conductor. Eddy currents flow in closed loops within conductors

## Do AC electrons travel great distances?

Topic: AC

### Question

January 3, 2015

I understand that in a.c., current/electron flow changes direction. My question is how is this concept link to a home appliance, say a CD player with a live and neutral wire plug to the socket? And does the change in direction of flow of current in the CD player goes all the way back and forth to the power station which is situated hundreds of km from home? Thank you in advance for taking time to answer.

Michael - Malaysia

25679

Although the electrons change direction, they actually move only a small distance. But the moving electrons affect electrons on both sides, such that the changes in direction starts at the power station and goes all the way to your device and back. It is somewhat like a water wave affects the water molecules nearby, but the actual movement of the water is small.

Some electric motors are set up to be powered by DC electricity, while others must use AC. Some CD players that use both batteries and wall outlets have a rectifier to change the current type to the type of motor used.

## Questioning information on frequencies

Topic: AC World Voltages

### Question

January 2, 2015

Your statements "Unfortunately, 50Hz AC has greater losses and is not as efficient as 60HZ. Due to the slower speed 50Hz electrical generators are 20% less effective than 60Hz generators. Electrical transmission at 50Hz is about 10-15% less efficient. 50Hz transformers require larger windings and 50Hz electric motors are less efficient than those meant to run at 60Hz. They are more costly to make to handle the electrical losses and the extra heat generated at the lower frequency." are patently wrong.

On the contrary, for motors, lower frequencies are better (which is why, near Niagara Falls, an old 25Hz network survived for many decades; and why railways use 16,7Hz and 25Hz in many parts of the world); only with electronic rectifiers this problem has vanished (but 60Hz motors are still NOT more efficient!). Frequency has nothing to do with losses in general - yes, there are connections, but there are good reasons why many frequences from 15 to 100Hz as well as DC have been tried. If you can read German, you might want to read this to understand a little bit of the background by googling for bulletin0817Neidhoefer.pdf

Best regards
Harald M.

- Germany

25678

Thanks for your comments. I removed the mentioned paragraph and updated Worldwide AC Voltages and Frequencies with better information.

## Wants to use a 240 volt generator in Bali

Topic: AC World Voltages

### Question

December 12, 2014

Hello,
We will be moving from Australia to Bali soon and would like to take my trusty generator with us but have a concern with power differences because Australian power is 240v 50hz where as Bali is 220v 50hz.
My generator is 3 phase 415v 50hz with single phase also 240v 50hz, the reason I want to take my generator is because my new Bali house is wired in with 3 phase [415v 50hz] and split to also use single phase [220v 50hz] what my concern is can I run my Ausie genset for emergency power only? I've been told [on the street] that I can as the genset my produce 240v, but the house power will a only use 220v, bit confusing? anyway any advise would be greatly appreciated.
Regards
Barry

Barry - Australia

25638

In general, the listed voltage is only an average. Usually, there is a variation of about 10%. That means you can probably use your generator for emergency power. Hopefully, you will not need to, but it is always good to be prepared.

I hope this helps. Best wishes for your life in Bali.

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