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Answers to Readers' Questions on Physical Science:

Generating Electricity

The following 39 comments and questions have been sent in. They are listed according to date.

List of first 10 items

• Does magnetic force push electrons in wire?
• Why do we use fossil fuels to make electricity?
• Difference between lap wound and wave wound
• Monitoring AC generator
• Wants to learn about electronics
• How does AC get into our homes?
• Who invented DC?
• How much eletricity does a maglev train need?
• Drawings on maglev trains
• Can a magnet being used weaken over time?

Next 10

Does magnetic force push electrons in wire?

Question

February 21, 2009

In an electric generator (split ring), does the magnetic force tend to push electrons along the wire, either toward or away from the axis?

- USA

17312

Answer

When a wire moves through a magnetic field, the field causes the electrons to move in a direction according to the direction of motion and of the magnetic fields. It is called the Lorentz Force. You could say the force pushes or pulls the electrons in the wire. See:
http://www.school-for-champions.com/science/magnetism_lorentz.htm

The commutator ring is a way to create either AC or DC electricity.

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Why do we use fossil fuels to make electricity?

Question

December 2, 2008

It's always struck me as odd that we burn fossil fuels to make electricity for electric cars which are supposed to cut down on the amount of fossil fuels we burn. How does this work out to our environmental advantage? Clearly, hydro-electric power and the like are cleaner, but is that the majority of the electricity supply?

Don - Vietnam

16884

Answer

In many countries coal, oil or natural gas is used to power in the electrical generators. On a large scale, electricity from these sources is more efficient than burning gasoline to power automobile.

If given the chance, many countries would use hydroelectric power. Nuclear energy generation of electricity does not pollute much, but there is the question of disposing of waste materials.

Moving away from using fossil fuels to create electricity is a direction that many countries should be going. The problem is that it is very expensive to abandon an old, polluting generating plant and building a new one that uses clean power to generate electricity.

Hopefully there will be a greater movement toward cleaner energy in the future.

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Difference between lap wound and wave wound

Question

August 24, 2008

which one is better and what is the difference between lap wound and wave wound winding machine?

v.s.venkatramaiah - India

16396

Answer

A lap wound armature is a parallel armature winding. Lap connections are used for high current, low voltage loads.

A wave wound armature is a series armature winding. Wave windings are used for high voltage, low current loads.

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Monitoring AC generator

Question

April 14, 2008

Name two important properties that are constantly monitored at the AC generating utility.

Daniel - USA

15729

Answer

Voltage and current are electrical properties that are monitored. But depending on the type of generator, they may also monitor its speed and temperature.

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Wants to learn about electronics

Question

April 6, 2008

basically i want to learn about electronics. what is electronics? how its produce? how it change ac to dc? every basic thing about an electronics.

nouman - Pakistan

15671

Answer

Electronics goes beyond simple electricity and is the study of electrical circuits. Such circuits are used to change AC to DC, change the voltage in DC and many other applications. Radio and television use electronics.

There are many good websites that explain electrical circuits. Unfortunately, we do not have much detailed information on the subject at this time.

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How does AC get into our homes?

Question

March 19, 2008

Thank you for your informative website. Can you please explain how AC electricity gets to our homes? I am very confused. So far, I know that the spinning of the armature within the magnetic field causes the current to switch directions. But if it keeps switching directions, how do the electrons flow to our homes to give us electricity?
Also, in our household outlets, there are three slots. One is the hot conductor, the others are neutral and ground? Does the neutral complete the circuit? Does it also connect to the ground? And the ground is for grounding?
Your help would be greatly appreciated.

Sue - Canada

15565

Answer

If you have a complete electrical circuit with wires going from the power station generator all the way to your house and back, movement of electrons starting at the generator will cause those nearby to move until those in your home wiring start to move. Think of a very long hose filled with water. Pressure at end will cause water to squirt out the other end almost immediately.

Now with AC, all the electrons have to do is to move a few centimeters and then change directions to power your appliances. This little back-and-forth motion is all that is needed.

Both the hot and neutral wires are needed to complete the circuit. The ground is used for safety in case the wiring allows extra DC electricity, which could cause a shock. In some cases the ground is attached to the neutral.

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Who invented DC?

Question

January 15, 2008

Which came first, DC or AC?

I understand that AC was invented by Nicola Tesla, in the late 1800s.

Who invented DC, and when?

Walter - USA

15142

Answer

Alessandro Volta is created with inventing the battery in 1800, which is the first source of DC. In 1832, Faraday made discoveries on the motion of electricity.

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How much eletricity does a maglev train need?

Question

January 10, 2008

how much eletricity does a maglev train need to work e.g. 150v. Also is there a equation to work out how much eletricity is beening produced by a dynamo, e.g. eletricity-to-mph, so like if a dynamo is spinning at 50 mph how eletricity would be produced.

richard - UK

15102

Answer

One part of a maglev train is holding up from the track. The force required would depend on the weight of the train. You could have powerful magnets or use electromagnets. Electrical power P = VI or volts times current. But the amount of force of the magnet depends on the current and the number of windings in the electromagnet.

The next part of the maglev train is propulsion. That is done by alternating the electromagnets at a certain rate to move the train along.

A good description on how maglev trains work is at:
http://science.howstuffworks.com/maglev-train.htm

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Drawings on maglev trains

Question

December 9, 2007

well do you hav any drawings that proves us this answer:
Magnetic levilating(maglev) trains have electromagnets on the underneath of the train that repel those on the track.As the train gets heavier ,indicators cause more current to be applied to the electromagnets to lift the train and keep it at a constant level.

Mei - United Kingdom

14939

Answer

See the page: http://www.rtri.or.jp/rd/maglev/html/english/maglev_frame_E.html for some good drawings.

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Can a magnet being used weaken over time?

Question

November 12, 2007

when a positive pole on a magnet repels a positive pole on another magnet,can they lose their polarity or even weaken over time?

- USA

14759

Answer

Magnets can lose their strength over time, but it is usually due to the affect of heat on the magnet and not the attraction or repulsion forces.

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