by Ron Kurtus

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

## List of next 10 letters

### Country

AC AC and DC current and resistance Afghanistan

AC Transformers How can I reduce my electrical costs? UK

AC Difference between right-hand rule and other names India

Generating Electricity Can electricity be generated in home? India

AC Transformers Specific voltage conversion with wire size USA

DC Want to use lightning as a power source India

DC Is the direction of the current opposite during charging? USA

DC Circuits Resistance when wire is bent Pakistan

AC Transformers Who was the father of transformer? India

Electrical Charges Evaluate vectors Nigeria

Next 10

First 10 letters

## AC and DC current and resistance

Topic: AC

### Question

November 14, 2011

I have question regarding AC and Dc current and resistance:
If we have the same voltage and resistance in AC and DC circuit, then why we have different current in different circuit.
thanks,

Abdul Sami - Afghanistan

22168

Assuming it is a simple circuit with a power supply and a resistor, there are a number of factors involved.

If the AC voltage is peak voltage, Ohm's Law or V = IR does not hold up. Since the AC voltage is a sine wave, the voltage must be RMS (root-mean-square), which is 0.707 of the peak voltage. In this case, AC and DC current should be the same.

If the AC circuit includes a capacitor and/or an inductor, the law does not hold.

## How can I reduce my electrical costs?

Topic: AC Transformers

### Question

October 31, 2011

this is an informative site. thankyou. I have been toying with an idea to cut domestic electrical costs. In a nutshell, and as a crude guide, i was wondering how energy consumption, from one 230v outlet, would conclude, if i connected a 110v transformer with a 230v intake into a household ssocket. then attach a larger 110v transformerthat converts back to 230v, with several output connections. theory being... create 4 or more 230 outlets from one 230 consumption point, via a drop down 110 transformer. your genius is appreciated

Neville - UK

22122

Electrical costs are usually measured in kilowatt-hours, which are thousands of watts per hour. (See Electrical Power).

AC transformers use power to convert the voltages. Putting them into your home system would actually increase your wattage use. Also realize that many devices are made for 230V and will not run effectively on 110V.

Some ways to cut domestic electrical costs are to start converting away from incandescent light bulb to the new low wattage bulbs, disconnect "always on" adapters from various devices. If an adapter feels warm, it is using electricity even if the device is off. Many remote control television sets draw energy all the time, so that they can turn on instantly. Also, many older electrical devices are very inefficient.

Also, simply being conscious of excess electrical use--such as leaving the lights on when no one is home--can greatly decrease your costs.

Best wishes in lowering your electrical costs.

## Difference between right-hand rule and other names

Topic: AC

### Question

October 31, 2011

Is the 'right hand thumb rule' and the 'right hand rule' same.
I am in a great confusion. Wikipedia says so. But the NCERT textbook give their definitions distinctly and without any relation.

Are they same or different? Basically they are different as they are rules for totally different things. But that might not prove that they have no internal relations. Please I need help.

The talk page of Right-hand rule in wikpedia contains discussion about the same things that may help you get my question more clarified.

Thank you. I love school for champions very much.

I searched the web many times but failed to get a clear answer. Also you may create an article about Right hand thumb rule so that those people like me can find the right answer. Also it will serve as a clear reference for separating the right hand thump rule and right hand grip rule.

Also I am thanking you for such a good site. It is this SCF that cleared my three year argument about AC. Electrons move to and fro in AC unlike DC where there is cumilation of electrons (which flows in one directions). I claimed the same thing when I was taught the AC generator at the school. No other site gave such a clear definition to me with a clear diagram.

Valchemishnu - India

22118

With the right-hand thumb rule, you are emphasizing the direction of the item indicated by the thumb. With the right-hand rule, you could be either considering the motion in the direction of the fingers or the value in the direction of the thumb. The right-hand grip rule simply makes sure the person is thinking of gripping the wire or such.

But since the difference is trivial, it is more common to see "right-hand rule" stated.

I am glad you've found the site helpful to you. Best wishes for success in your studies.

## Can electricity be generated in home?

Topic: Generating Electricity

### Question

October 23, 2011

i want know can electricity generated in home

Rohan - India

22107

People use solar panels, wind turbines, and gasoline generators to generate electricity for the home. Unfortunately, it is often expensive to set up such a system.

## Specific voltage conversion with wire size

Topic: AC Transformers

### Question

October 16, 2011

Please provide me with the laws of his birth simplified to convert 500 volts to 220 volts note that the number of alliances 20 laps and the type of binding sequence and the wire diameter 1.80 mm, and thank you

ali - USA

22085

I'm sorry, but we don't have that information.

## Want to use lightning as a power source

Topic: DC

### Question

October 14, 2011

We doing an project in lightening as source of electrical energy. But we are obstructed a problem. That since it is a high voltage source, it has to be step down. But since it is a d.c it cannot step down directly. can you please help us.

- India

22075

The biggest problem in using lightning as a source of electrical power is the fact that it is often uncertain when the lightning bolt will strike. In an area where there are many thunderstorms, you might be able to set up a lightning rod to attract the lightning bolts. One idea was to have many such towers to increase the chances of a lightning strike.

Before you think of stepping down the voltage, you need to be able to store the power in some way.

One thought is to store the power in a huge capacitor, so that the DC can be discharged slowly at a lower voltage. However, a lightning bolt sends its power so fast that a capacitor cannot be fully charged.

An interesting article on the subject is: Harnessing Lightning and Using the Electricity.

I hope this gives you some ideas.

## Is the direction of the current opposite during charging?

Topic: DC

### Question

October 10, 2011

IN A 12 VOLT DC CIRCUIT IF CURRENT FLOWS FROM NEGATIVE TO POSITIVE. WHEN A BATTERY CHARGER IS CONNECTED TO A BATTERY DOES CURRENT FLOW FROM POSITIVE TO NEGATIVE?

BILL - USA

22055

Yes, the current is in the opposite direction during charging than when during use or discharging. You can think of it as adding electrons to the chemicals that store the current.

## Resistance when wire is bent

Topic: DC Circuits

### Question

October 4, 2011

you are doing very well, i am very thankful to you, i have a question sir .do bend in wire affect its electrical resistance? sir i have another question. describe a circuit which will give a continuously varying potential.

owais - Pakistan

22040

When a wire is just curved around an object, the resistance does not change. However, when the wire is sharply bent, it stretches the metal and slightly changes the resistance. It would be an interesting experiment to try to measure the difference. I am sure it is very small.

By adding a variable resistorlike a rheostatin a series circuit, you can vary the potential.

## Who was the father of transformer?

Topic: AC Transformers

### Question

September 16, 2011

Who was the father of transformer ?

Bhanu - India

21992

In 1886, American William Stanley invented the induction coil, or what is known today as a transformer.

## Evaluate vectors

Topic: Electrical Charges

### Question

September 1, 2011

Evaluate A^B, where A and B are vectors in space with i, j, k as the unit vectors

Stephen - Nigeria

21938

See Vectors in Gravity Equations for some information on using vectors.

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## Resources and references

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