“How does a magnet become a magnet?” asks Ava (11)

A brilliant question Ava. I asked my team for their thoughts.

Yes team you are quite right there are some limitations to magnet making. The main one is that only certain metals can be made into magnets. These metals are called ferromagnetic metals.

Included in this group are the metal iron and the alloys of iron with the metals cobalt, nickel and some other rare earth elements .

It is thought that in these metals (including iron) have some electrons called ‘free electrons’ (not sure what an electron is, then go to Science Master Special – Atoms and Atomic Structure). It is these ‘free electrons’ that are involved in magnetism. In the alloys the  ‘free’ electrons align themselves with the magnetism of the external magnet, making a (for the alloys) a permanent magnet. For iron alone the magnetism is only temporary and you can test this in the experiment below.

 

Look at the short video I have made below. In the ferromagnetic metal (iron alloy) crystal domains you will see free electrons. In the metal these will be moving freely. As they begin to interact with the external magnetic field, they begin to align themselves, making a permanent magnet.

 

 

 

 

 

 

 

 

 

 

 

Pete (10) asks “What is the pitch of a sound?”

Thank you team.  Lets first look at the motion of the particles. You suggest that the motion of the particles is in the form of waves. I think that is quite difficult to imagine but I think I have an example that will help illustrate this type of motion. Look at what happens when you drop a pebble in a pond. The pebble, when it hits the water, it creates  one vibration.

 

 

 

In this image the sound is produced by the piston creating the waves. Notice the wavelength, that is important. If we can manipulate the piston, make it go slower or faster  we can change the wavelength. Changing the wavelength is changing the pitch, think about that.  How does the sound change?

Try blowing over, or tapping, some bottles.

 

Pitch and Frequency ..Test your hearing a little bit more …….

In the video below you can see and hear how the pitch of the sound and the wavelength change together.  We measure wavelength in units called Hertz. 1 Hertz is one cycle per second. In the image above imagine that it takes one second to get from the flute to the ear. Then there are 8 cycles in the top sound is so frequency is 8 hertz and there are 3 cycles in the bottom sound so the  wavelength is 3 Hertz.

You can now test your hearing.    Take Care….make sure you have control of the volume.

 

 

Thanks to
Orion Lawlor, for the water ripples video, Published on 9 Jan 2011
Earmaster at https://www.earmaster.com/music-theory-online/
The ISVR from the Institute of Sound and Vibration Research, University of Southampton.
The Sound Video, unknown but thanks.

Ellie (12) asks “What are the damages of hurricanes?”

Great question Ellie. I was going to ask my team to tackle this, however for some reason the question was left unanswered so to apologize I think I will try to answer it myself.

How is a hurricane created?

Air is made up of tiny molecules. When molecules are heated, they move faster. As they move faster they become become spaced farther apart, which makes the air less dense – meaning that there are fewer molecules in a given volume. This also means that the air has a lower overall pressure – pressure is the push of the gas on it’s surroundings. In comparison, cold air is made of more tightly packed molecules, and so it is denser and has relatively higher pressure.

The warmer, lower pressure air begins to move upwards and therefore it creates space below it which is filled by the colder higher pressure air. The warmer air ‘floats’ on the colder air. It also carries with it water vapour – water that has evaporated and contains lots of energy. A wind begins to be created. The hotter the air near the surface of the sea, the lower the pressure and the faster the rise.

As this warm air gets higher it begins to cool and also the water vapour that would have risen with it begins to turn back to water. A cloud begins to form. The energy of the condensing water vapour is given to the cloud.

The cloud of colder air and water vapour begins to move in circles (because the Earth is rotating). It meets other storm clouds. The hurricane is forming and is being fed by the warm air close to the warm sea.

What are the damages of the hurricane?

The strong winds of a hurricane can push water up and onto land. This water can cause major flooding and damage to homes, cars, and boats. Heavy Rains – Hurricanes can cause heavy rains that flood places inland and away from the center of the storm.

This video will help explain the formation of the hurricane.

 

 

 

“Why does the sky go green when it hails?” asks Swifty (11)

What a question? Thanks  team for your thoughts. To me it seems to be a unique mixing of the colours from our sunlight. We know that the blue sky is because of the blue part of the spectrum of colour that comes from the white light from the Sun.

Some of the blue part of that spectrum of light is scattered when it hits the molecules of Oxygen and Nitrogen in Earth’s atmosphere. So blue coloured light illuminates the daytime sky. We know that when we see a sunset we can see a red sky in the distance and that is because we are looking at the Sun through a lot more atmosphere than we would do in a normal day. This is the dust that is in the atmosphere. In the experiment the milk acts as a ‘dust’ in the water.

I attach a NASA video that explains this then I will tell you my ideas about a green sky.

My thinking, and that of some others, is that the green sky is linked to the storm clouds (the background image above, was a pause in the hailstorm that the cyclists were experiencing). These were preventing some of the sunlight reaching the viewer who saw a yellow light mixed with the blue sunlight. the mixture of these lights could have caused the green light (a cyano type of light, like that below).

Very happy to hear comments and questions. Remember science development is about admitting your ignorance and my thoughts above are just thoughts. You and I need to do some further investigations.

Revised 10/1/18 to include experiment and colour example.

Keith (13) asked a question about thermal papers in cash machines.

Keith’s question
More and more places are using thermal paper as a form of receipt paper for customers. With time the information fades. How can one scientifically go about recovering information which may have faded from thermal paper.

Keith, many thanks for the question. I never realised that thermal(heat sensitive) paper was used in so many places and that it is also the basis on which the polaroid camera worked.

Thermal paper is made using a collection of dyes which exist as colourless crystals that become coloured when they interact with an acid.


For those who enjoy their chemistry you might have come across adding a dye called phenolphthalein to an acid solution. The dye changes from colourless to a deep purple.

The applied heat (from the cash register machine) melts a layer in the paper which contains acid crystals. The liquid acid then interacts with the layer below it which contains a colourless crystalline dye which changes colour as the acid interacts with it.  The print then shows. The acid quickly becomes crystalline again.

Over time the print does begin to disappear.

A little investigation.

Obtain an old till receipt which your adults do not want to save. Put it onto an ironing board and with a hot (care) iron, iron it.

Stop

To make it more scientific predict what you think might happen before you carry out the experiment. Any ideas, if so you have a hypothesis.  Now find a very old (fading) receipt and using a hair drier blow warm air onto the BACK of the receipt. Again predict.

I think I’ll stop there. Many thanks for the question Keith. Please comment or ask another question.

Questions on electricity were asked by Gavin (10), Tegan (10) and Hayden (9)

Gavin asked “Why does the energy flow through the wires?”

Tegan asked “How does electricity work?”

Hayden asked “How do batteries springs and wires make a complete circuit?”

So how does this compare with a modern day battery. lets have a look and think about Gavins question.

Hayden and Tegan. In the circuit below the  energy flows around the circuit when the switch is closed. Why? What are wires made of? What is special? If the wires were plastic do you think electricity would be able to pass through it? Try and make your own circuits with different materials.

Electricity is linked to the passage of negatively charged electrons. These were very comfortable in the battery until it was connected to a circuit (a circuit is a continuous pathway) and the switch was closed. The circuit gave the electrons (negatively charged) a passage to the positively charged end of the battery. Electricity (electrons) flowed and accompanying the electrons was energy. Look at the Science Master Special on Energy and why not try the Circuit Quiz.

 

Do not play with mains electricity. It is very dangerous and could kill you.

Lexi (9) and Jaeda (9) and Cadence(8) asked a question on “Minerals”

Lexi, a nice question, a lot of elements are found within the form of a mineral. I shall let my team introduce the answer to this question.

Jaeda. You asked a question on crystals and why are they so expensive. This is not  a science question however most crystals are minerals so this question is also addressed to you.

Cadence . You asked about talc, which is a mineral.

All minerals are found in rocks. It is thought that some are created by the magma (lava) from volcanoes while other were formed in the Earth’s mantle and have reached the surface through earthquake activity. The minerals created from volcanoes have smaller crystals (probably cooled faster), minerals created more slowly in the mantle consist of bigger crystals. All of the minerals are created by a chemical reaction.

A lot of minerals are mined, dug from underground shafts. A lot of minerals have the elements Silicon and  Oxygen in them.Talc is a mineral of the elements Magnesium, Silicon and Oxygen and is mainly found in Japan and the United States.

Have fun and watch this video on minerals.

Thank you Lexi, Jaeda and Cadence. If you want to comment on this post please feel free to do so in the Reply box below. Or why not ask another question.

Could the Earth’s core be hotter than the Sun? asks Brooke (9)

Brooke. When earthquakes occur ( For how they occur see this question) you get a seismic wave travelling outwards from where it occurred. Imagine an explosion, a rock cracking a noise bigger than anything  you have experienced.  It would create the biggest sound ever, shake the ground more than it has ever been shaken and send a signal to the rest of the Earth that the earthquake had happened. It is this seismic wave of spreading energy that has helped scientists discover the structure of the inner Earth. The waves spreads out in all directions and some of them pass through the centre of the Earth. If you look at the waves on the other side of the Earth you can examine them and find out what they have travelled through.

It is now thought that the temperature of the inner core is close to 7000 degrees K (Kelvin). It is however not a liquid , because of the pressure of all the stuff on top of it. It is therefore a solid iron core at about 7000 degrees K…which is close to the outer temperature of the Sun.

(0 degrees K=273 degrees Centigrade so 100 degrees Centigrade = 373 degrees K )

Hello (13) asks “How do tectonic plates work and influence earthquakes?”

Quite right my friend it’s all about convection. Warm water, air, oil, or any liquid/gas stuff  will move upwards (rise) when it is heated. Why. Think about it.

Lets think of an experiment (this is a science blog) where we can test this idea and then move on to the question that Hello asked.

The experiment

You will need a beaker of water, some pencil lead, 3  A batteries, two leads with attached crocodile clips and some food colouring and a dropper

Connect the pencil lead to the batteries using the leads. As the electricity passes through the pencil lead, the pencil lead will heat up. Drop the attached lead into the water. Look carefully at the water, what is happening. If you put a small screen behind the beaker of water and shine a torch on the water you will be able to get a better view of what is happening to the water.

OR

Drop a small amount of food colouring into the water.

Hopefully what you will see are convection currents that have been created by the water close to the lead  warming up and beginning to rise. The next question is WHY.

Warning. Do not use mains electricity. It could be very dangerous and kill you.

Why does the water rise?

When the water particles(molecules) come into close contact with the heated pencil lead they gain kinetic energy (see Science Master Special Energy), they move faster. The water molecules spread out so that in any given space there are less water molecules (less dense). This means that gravity comes into action and the colder water can begin to move into the space where the warm water was. The warmer water ‘floats’ on top of the cold water. The cold water then gets warm and and more cold water moves in and the original warm water floats up higher in the beaker. As the warm water rises it gets colder and more dense and eventually will join the column of cold water that is moving (by gravity) downwards toward the hot pencil lead. Wow…..I hope you can see the picture

The movement of the tectonic plates is caused by convection currents and it is this movement that can cause earthquakes. Hopefully when you watch the excellent video below you will see the links.

Hello. If you would like to question anything, please make a comment or ask another question.

 

 


(Anyone reading this post who wants to ask a question or make a comment please feel free to do so)

Andrew (11) asks “How do you make plasma?”

Andrew, quite an ‘exciting’ question. To find out how we make plasma lets look first at atoms and their structure. My team will do this and then I will come back to talk about plasma.

Andrew. I will be talking about a Neon atom. The Neon atom has 4 protons in its nucleus with 4 electrons orbiting it. Does that give you a clue to my plasma source?

The most familiar plasma sources that you might come across are Neon light tubes and lightning.

Firstly let us look at what plasma is. It is defined as a hot ionised gas which has an equal number of protons and electrons existing in the same space. Lets look at a neon light tube.

In the tube the Neon atoms lose electrons to the positive electrode, the remaining  Neon positively charged atoms (they have lost an electron) are attracted to the negative electrode. Lots of exchanges of electrons take place during this process and this ‘excites’ the electrons and creates the  plasma environment which gives of energy in terms of light.

Really hope that this helps. Please tell me if you do not understand bits of it or ask another question.

(Anyone reading this post who wants to ask a question or make a comment please feel free to do so)

 

Edited 11/10/2017 Pictorial representation in image changed to ‘drawing’. Text size on image changed.