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Science Feedback

by Ron Kurtus

Readers have sent in a total of 4977 comments and questions on Science issues. They are listed according to date.

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



List of next 15 letters

Title

Topic

Country

Conducting high voltages through air Electricity Bangladesh
 
Exceptions to the trend in densities Density Factors Pakistan
 
I love to study sound Sound Waves USA
 
Discuss kinetic theory of matter Kinetic Theory of Matter Liberia
 
Do not understand electromagnetism Electromagnetism USA
 
Discharging accumulator Electromagnetism Nigeria
 
Increase in density beneath volcano Density Factors Ghana
 
Should the force be inifinte is the separation is zero? Force Between Two Objects USA
 
What is the pressure for 20N force? Pressure USA
 
Using a 220V fan in the US AC World Voltages USA
 
How does a lightning bolt occur? Static Electricity Sparks Uganda
 
Demagnetise a magnet Basics of Magnetism Zambia
 
Shocks dog with static electricity Reducing Static Electricity Shocks USA
 
Which pole carries a positive charge? Basics of Magnetism USA
 
Energy needed to melt a gram of ice Heat for Ice to Steam USA
 

Next 15 letters

 




First 15 letters


Electricity

Conducting high voltages through air

October 16, 2015

Question

Is it possible to conduct high voltage(11000 to 33000)voltage through the air ?
In what condition air can be transformed as a plasma.....?

Taslimur - Bangladesh (26448)

Answer

At voltages above 33000 V, the insulation of air breaks down, allowing electrons to pass through the air gap. If the air is very humid, electrons will flow at lower voltages, such as 11000 V.

Air breaks down to become a plasma at electrical field strengths of greater than 33 kilovolts per centimeter.

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Density Factors

Exceptions to the trend in densities

October 15, 2015

Question

My question is!!
Kindly tell the few major exception in the trend of density among periodic table

aysha - Pakistan (26443)

Answer

It seems that the inert gases, such as helium, neon, argon, etc, are exceptions to the density trend in the periodic table. See Periodic Trends for an explanation.

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Sound Waves

I love to study sound

October 12, 2015

Question

i love sound.

eve - USA (26435)

Answer

I am glad you love the subject. It is very interesting and useful.

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Kinetic Theory of Matter

Discuss kinetic theory of matter

October 11, 2015

Question

Discuss the kinetic theory of matter and base on collision temperature. Pressure. Particles, expansion

Alfan - Liberia (26432)

Answer

You can use the lesson material to discuss the features when you consider the effects of the motion of atoms and molecules. Their collisions result in the effects of temperature, pressure and expansion.

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Electromagnetism

Do not understand electromagnetism

October 8, 2015

Question

PLS. I AM SS 2 STUDENT. ACTUALY, I AM YET NOT UNDERSTAND WHAT AND HOW ELECTROMAGNETISM TALKS ABOUT

YAHAYA - USA (26427)

Answer

When you wrap a wire around a bar of iron and send direct current (DC) electricity--like from a battery--through the wire, the iron rod becomes a magnet. This is called electromagnetism.

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Electromagnetism

Discharging accumulator

October 8, 2015

Question

pls.i need a detail explanation on how to discharge an accumulator or a secondary cell

Sani - Nigeria (26428)

Answer

See Basics About Discharging for some information. I hope that helps.

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Density Factors

Increase in density beneath volcano

October 2, 2015

Question

what causes an increase in density beneath a recently active volcano?

maud - Ghana (26415)

Answer

It could be that the molten lava can be compressed, thus increasing the density over solid rock.

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Force Between Two Objects

Should the force be inifinte is the separation is zero?

September 28, 2015

Question

How is it that if the distance between the 2 objects is zero that you can pull the objects apart. Hypothetically speaking the force between the 2 objects should be infinite if the distance between them is zero.

Karim - USA (26412)

Answer

The distance between objects is measured from their centers. Thus, since they have some size, and if they are touching, there still would be a separation.

If the particles were points, and they were touching, there separation would be zero and the force would be infinite.

One thing to note is that when particles approach an extremely small size, Quantum Wave Mechanics takes hold, and the particles become considered as waveforms. Different rules then apply.

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Pressure

What is the pressure for 20N force?

September 27, 2015

Question

If force is 20N and area is 10cm^2 then what is pressure

- USA (26408)

Answer

Pressure is measured in N/m^2. So you will have to change cm^2 into meters squared.

100cm = 1m
m/100 = cm
m^2/10000 = 1cm^2
m^2/1000 = 10cm^2

Pressure = 20(1000)N/m^2 = 20000M/n^2

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AC World Voltages

Using a 220V fan in the US

September 26, 2015

Question

Hello,

I am moving from Cambodia to United States after spending sometime here. I bought a wall fan that I really liked and it operates at 220V 50Hz. The house I will be living in the U.S has a 220v wall outlet, I wanted to know the following:
Since there is 220V outlet, the voltage on the fan will be okay. True/False
Does it matter if I am running a 50Hz fan on a 60Hz?
Will it harm the rest of the electricity in the house? Is it safe?
Is it more expensive / less efficient to run a 220v/50Hz device then 110v/60Hz Device?

If you can share your knowledge I would really appreciated it.
Thanks,
Sam

Sam - USA (26405)

Answer

220V outlets in the house are usually used for stoves and electric clothes dryers. You may have to get a receptacle adapter. The 220V should be fine but at 60Hz, it may be running faster. I'm not sure if that would harm your fan. It would be good the check with the manufacturer.

It should not affect the rest of the house electricity.

Electrical cost is based on wattage, which is voltage times current. I think the power output (and cost) should be about the same for both devices.

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Static Electricity Sparks

How does a lightning bolt occur?

September 20, 2015

Question

how does a lightning bolt occur

budali - Uganda (26392)

Answer

See Static Electricity and Lightning for an explanation.

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Basics of Magnetism

Demagnetise a magnet

September 17, 2015

Question

How can u demagnetise a magnet and how can u make a material to become a magnet eg iron?

peter - Zambia (26386)

Answer

There are demagnetizer devices that you can purchase. However, you can also remove the magnetic properties of a material by sufficiently heating it.

You can turn a piece of iron or steel into a magnet using electromagnetism. See Electromagnets for information. But note that soft iron will lose its magnetism fairly rapidly. Harder steel will hold onto its magnetism.

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Reducing Static Electricity Shocks

Shocks dog with static electricity

September 12, 2015

Question

I have real issues with static, not with metal but with animals and people. I try to grab metal before I touch my parrot (actually she won't let met toutch her until I hold her cage) but I'm shocking my German shepherd and he's starting to growl at me. I do this all year long, worse in the winter. I killed watches.Is there something I can do to control this?

marion - USA (26377)

Answer

When people generate a lot of static electricity, it is usually caused by a combination of very dry skin and clothes made of synthetic materials.

Try skin moisturizer and wearing 100% cotton clothes (including underwear). Hopefully, that will help.

One of the static shock eliminators from Amazon.com as listed on Reducing Static Electricity Shocks is quite inexpensive and may help, especially when used before petting your dog.

Best wishes in solving this problem.

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Basics of Magnetism

Which pole carries a positive charge?

September 11, 2015

Question

Which pole of the magnet carries the positive charge and which the negative? Is north positive or negative?

Ivey - USA (26374)

Answer

Neither magnetic pole carries an electrical charge. When a wire is passes through the magnetic field between the N and S poles, electricity will flow in the wore, according to the direction of motion of the wire.

See Generating Electrical Current for more information.

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Heat for Ice to Steam

Energy needed to melt a gram of ice

September 10, 2015

Question

determining: the heat of fussion of ice

how much energy is needed to melt a gram of ice at 0 degree celcius?

- USA (26370)

Answer

The process a solid to a liquid is called the "enthalpy of fusion". The value for ice/water is 333.55 J/g.

Thus, it would take 333.55 joules to melt 1 gram of ice.

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Next 15 letters


Misc


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