List of Topics


Physics Feedback

by Ron Kurtus

Readers have sent in a total of 853 comments and questions on Physics issues. They are listed according to date.

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

List of next 15 letters




Using adapter between plugs AC World Voltages New Zealand
How fast is a magnetic impulse? EM Waves USA
Is time static? Time USA
Thoughts on Absolute Zero Temperature Limits USA
Approved fuel containers Basics of Static Electricity Australia
Torque and increased diameter Force and Torque USA
Annoying ad on page Units of Frequencies and Wavelengths USA
Using 60Hz on 50Hz circuit AC World Voltages USA
Applications of viscosity Viscosity India
Suggested resource Resources India
Update Guyana voltage AC World Voltages Suriname
Equation different in textbook Doppler Effect India
Using static electricity to charge phone Basics of Static Electricity Egypt
Uses for friction Uses of Friction Nigeria
References on electrostatic painting Uses for Static Electricity Egypt

Next 15 letters


First 15 letters

AC World Voltages

Using adapter between plugs

June 11, 2017


can I use an appliance from south Korea - 220v in New Zealand 230v ? from your chart it would also appear that the frequency will be different also will this cause problems? thirdly the plug types are different is it ok for an electrician to change the plug from c to l

Tina - New Zealand (28086)


The voltage difference should not affect things. However, a 60Hz appliance might perform slower with 50Hz. If there are timers or clocks involved, it might make a difference. It is good to check with the manufacturer website to see if things would work sufficiently.

An adapter plug could be used if the prongs are different. An electrician should be able to make the proper connections.

Best wishes for successful use of your appliance.

Return to List

EM Waves

How fast is a magnetic impulse?

June 3, 2017


Have the effects of magnetism (attraction-repulsion) ever been quantified into speed? How fast is a magnetic impulse?

James - USA (28072)


Magnetic, electrical, and gravitational impulses all move at the speed of light. Typically, a magnetic disturbance will cause an electrical disturbance, resulting in an electromagnetic wave, which also travels at the speed of light.

Return to List


Is time static?

June 2, 2017


Love your site, Thank You!

Subject: Relativity/Time
We humans understand time as past, present and future.
The Past is our Memory
The Present is our Current Condition
The Future is our Expectation

Is it possible that Time is static?

We exist in a series of static universes that we register as the duration or "flow" of time.
Even at Planck time there is duration.
Duration is change in the Universe.
By splitting any change into time segments, every change has a beginning, a duration and an ending.
Even the emission of a photon.
It is a static photon, it starts to move, continues to move and stops moving when acted upon or reaching the desired destination (Planck Length).
During the moment when it starts to move there is duration between its static point and its next static point.
There is even duration between the change of static points. Like a buildup to change similar to a potential charge of time. I'll call it a Duriton.
Duritons occur faster than can be measured by our technology. Just because something can't be measured doesn't mean it can't exist.
Our lives are a series of duritons that we register on a massive scale to simulate continuity.
Is it safe to say that we exist in a constant flow of individual duritons, remembering the past as the present?

Thank you.

tMic - USA (28069)


The whole concept of time is difficult and complex.
As far as humans go, the sensing of time seems to vary with age. See Sensing Time. Thus, is time different for different people?

At the quantum level of matter, movement is in "quantum jumps" instead of being continuous. Likewise, since time is related to motion, it too could be in quantum increments. Thus, you could think of time being static in between those jumps. Your idea of a "Duriton" might fit within that area.

In some theories, time is considered a fourth dimension. It can curve just as space can curve.

Keep up the good work in pondering these issues.

Return to List

Temperature Limits

Thoughts on Absolute Zero

June 2, 2017


Subject: Energy/Absolute Zero

"At the physically impossible-to-reach temperature of zero kelvin, or minus 459.67 degrees Fahrenheit (minus 273.15 degrees Celsius), atoms would stop moving. As such, nothing can be colder than absolute zero on the Kelvin scale."

However, is there a scale that measures colder than Zero Kelvin (Absolute Zero)?
Lets call that True Absolute Zero (TaZ)

We know that matter is composed of energy and the reversion of matter to energy is the basis of the atomic bomb. If matter is made of energy then is there a scale that measures energy down to its baseline?

An electron volt (eV) is not a baseline value of energy because we measure fractions of eV. Lets call the baseline value of energy an "Eneron".

Every atom has movement within itself on diminishing scales.
Quarks, Leptons and even Bosons have movement in their spins.
Temperature is movement. Frozen means no movement. True Absolute Zero would imply that all movement has stopped.

Energy implies movement. "Its energetic"
At TaZ (True Absolute Zero) wouldn't energy stop? If an Eneron stops, is it no longer energy. Can it restart without another Eneron acting upon it?

"The first law of thermodynamics, also known as Law of Conservation of Energy, states that energy can neither be created nor destroyed; energy can only be transferred or changed from one form to another."

If the Eneron stops it is no longer energy and thus the first law of thermodynamics is wrong.

In the Universe there exists a potential for everything to eventually and completely freeze over time. Everything in existence reaches true absolute zero and all energy stops. With no energy to initiate movement (heat), there is no action to generate more energy.

Thank you

tMic - USA (28070)


The requirements for Absolute Zero are not only that atoms stop moving or have zero kinetic energy, but also that their internal potential energy is zero. In reality, the binding forces of the atoms would reach zero, such that the particles would fall apart.

Even Quarks, Leptons, and Bosons would not move or spin.

Matter is really not made of "energy". The energy released in an atomic bomb, such that the mass of the material is reduced, is in the form of electromagnetic radiation or photons. These particles do not have a rest mass, but they do have momentum as they move.

An electron volt is the unit of energy equal to the work done on an electron in accelerating it through a potential difference of one volt.

I hope that gives some explanation. Keep up the good work in creatively looking at these Physics concepts.

Return to List

Basics of Static Electricity

Approved fuel containers

May 12, 2017


Hi guys

I am an ex firefighter (28 years) and are now involved in teaching fire safety. I deliver training to fuel company staff. One of the topics covers using the correct "Approved Fuel Containers" for transport of fuel (Petrol).

My question is, are the containers manufactured of a plastic that incorporates a conductive substance to dissipate electrical charge? If they are that is great but, my thoughts are they are as conductive as any other plastic container. If this is the case, how does the electrical charge dissipate when filling the fuel container on the ground. In theory it is non-conductive.

My thoughts are that all plastic will conduct electricity to a degree. Not enough to allow enough current to flow to power a light bulb if used in a circuit but will allow enough current to flow causing a static spark. I am thinking milliamps as compared to amps will flow.

I am attempting to confirm that the only difference between an approved fuel container and a non-approved fuel container is its solid construction of plastic that will not deteriorate by petrol.


Fred - Australia (28044)


Static electricity consists of electrical charges on the surface of the container. Approved Fuel Containers usually are made of a hard plastic material that does not collect charges as mush as a container made of a soft plastic. You can tell by rubbing a balloon on the container and see if it gets charges such that it sticks to some surface.

The big concern is having charges collect on the container and getting a static spark that would ignite the fuel fumes. If the container is on the ground and you are also on the ground, you are both "grounded" such that charges readily flow to the ground. But if the container is on a plastic bed of a truck when being filled, a spark may jump from the container to you are the filling tube, thus igniting the fumes.

Note that the issue isn't whether plastic conduct a little electricity, but is it whether charges on the surface will jump and cause a spark to some other item or person on the ground.

It isn't a simple situation, and I hope this clarifies things somewhat (or does not confuse the issue!)

Best wishes for success in your fire safety classes.

Return to List

Force and Torque

Torque and increased diameter

May 6, 2017


Im interested in torque on a round object.
I'd like to know if you increase the diameter of the object by say 10% how does it affect rotational torque.

Jon - USA (28038)


Since T = FR, increasing the diameter by 10% increases the radius R by 20%. Thus, the torque T would increase by 20%.

Return to List

Units of Frequencies and Wavelengths

Annoying ad on page

May 2, 2017


While on the page using Chrome on a Mac, the page is regularly refreshing and jumping around, making it very difficult to use.

The video ad in the upper right cannot be turned off, and is very distracting.

I like your material very much--you are clear, give enough information without assumptions as to how much a person knows and progress clearly. Thanks!

Stephen - USA (28033)


Thanks for the feedback.

The ads on my site are through Google AdSense and are not supposed to be annoying. I also hate going to websites where they have videos with loud sound. You typically can click the Pause button on the lower left corner to stop the sound and video.

If that does not work, let me know what company the ad is from, and I'll contact Google to block them from my site.

Return to List

AC World Voltages

Using 60Hz on 50Hz circuit

May 1, 2017


I buy a Makita hp1630k drill 220v 60hz question:can I use this drill in Europe 220v 50hz

Jani - USA (28031)


The drill should work, although it may run a little slower. It is good to contact the company customer service to see if they recommend using an adapter.

Return to List


Applications of viscosity

April 18, 2017


Sir please explain: Applications of viscosity in our daily life in an easy way.

Kummari - India (28007)


Viscosity can be thought of as the "thickness" of a liquid or fluid. One application is in lubricating a machine. Oil or grease has a greater viscosity than water and thus it works better at reducing friction and wear between the parts.

High viscosity means the material is slow-flowing, like molasses or toothpaste. You wouldn't want them to have low viscosity, such that they were runny.

I hope that helps your understanding,

Return to List


Suggested resource

April 2, 2017



I am a writer of science topics and have a website which is about teaching the kids about science with interesting articles and easy-to-do experiments. its motive is to provide science education free of cost and free of ads to enhance the interest. I want to deliver my website to every science student. I will thankful to you, if you can check the website's physics section at and include in your physics resource page under the name "Physics for Kids" for the students.
I look forward to hear from you soon. Thank you


Abdul Wahab - India (27980)


I added a link to Fun Science for Kids at Physics Resources. Best wishes for success with your website.

Return to List

AC World Voltages

Update Guyana voltage

March 24, 2017


Re: World list of AC household voltages has an error:

Guyana 60Hz = correct but 240V? No Way.!

Some 110 or 120V . Check it out!

Happy to see a comprehensive AC voltages listing.


Jozef - Suriname (27956)


Thanks for the input. The standard AC voltage in Guyana is 220 or 240V. However, there are many areas in the country that use 110VAC.

I updated the list to reflect state both voltages.

Return to List

Doppler Effect

Equation different in textbook

March 2, 2017


In textbook eq. is given in terms of v, but in your lesson its given in terms of lambda.

Rajendra prasad - India (27919)


The velocity of a waveform--especially for light or sound--is often designated as "c" instead of "v". Lambda represents the wavelength.

You can also rearrange the equation to be wavelength = velocity/frequency.

Also see Doppler Effect Equations for Sound.

Return to List

Basics of Static Electricity

Using static electricity to charge phone

February 24, 2017


if i somehow generated this static electricity, how would i use it for turning on something ?
and how much electricity needed to make a phone charger work for example ?

nada - Egypt (27904)


Static electricity is static and does not move like DC or AC electricity.

Most phone chargers use alternating current (AC) electricity to charge the batteries. However, there are some new chargers that use the wireless electricity signals to charge the batteries.

Static electricity can be used to generate sparks. That might be able to turn something on. But also, the sparks can cause damage to electrical devices.

Return to List

Uses of Friction

Uses for friction

February 23, 2017


List 12 uses of friction and disadvantages of friction

ade - Nigeria (27902)


There are some items listed on the Uses of Friction and Problems Caused by Friction pages.

You can look around you to see many other examples of uses and disadvantages that are similar.

Return to List

Uses for Static Electricity

References on electrostatic painting

February 20, 2017


I am Working on A project On High Voltage Engineering and i need any Reference talking about Electrostatic Painting
Best Regards

Mahmoud - Egypt (27892)


Some websites explaining the basics of electrostatic painting are:

Electrostatic coating

Electrostatic Spray Painting Basics Explained

How Does Electrostatic Spraying Work?

I hope that helps. Best wishes for success in your project.

Return to List

Next 15 letters


Questions and comments

Do you have any questions, comments, or opinions on this subject? If so, send an email with your feedback. I will try to get back to you as soon as possible.

Share this page

Click on a button to bookmark or share this page through Twitter, Facebook, email, or other services:


Students and researchers

The Web address of this page is:

Please include it as a link on your website or as a reference in your report, document, or thesis.

Copyright © Restrictions

Where are you now?

School for Champions

Physics Feedback

Subjects in website

Let's make the world a better place

Be the best that you can be.

Use your knowledge and skills to help others succeed.

Don't be wasteful; protect our environment.

You CAN influence the world.

Live Your Life as a Champion:

Take care of your health

Seek knowledge and gain skills

Do excellent work

Be valuable to others

Have utmost character

Be a Champion!

The School for Champions helps you become the type of person who can be called a Champion.