Blog blockage with a helping of GCSE banter

As unlikely as it seems, I live an actual life in the real world, and have been busy in the past week.

Also in the real world, GCSE results have recently been released, and an unprecedented number of students are celebrating academic success. Well done!

Although there are critics among us who claim that the reason behind this is the unprecedented ease with which an A*-C grade can be achieved at this level of study.

I know of former fellow secondary school pupils who did indeed breeze through this part of education without bringing the tensile stress to their cranium to extremes, but I remember feeling really quite stressed for these exams. Now looking back, I could probably, no arrogance intended, have fitted in an extra extra-curricular sport to my then-schedule without compromising my results.

In fact, I felt this way already at the halfway stage between AS and A2. So, why is it, that never until we have moved on to the next part of our lives, do we realise how good we had it? And why do some of us, self included, cease to understand the struggles of yesteryear once it has passed? Is it just because we are too busy lamenting our current lifestyles?

Perhaps so. For now, I think we should leave the poor, hormonal souls of 15 – 16 year olds alone as it will soon dawn upon them that while the pressure may have pushed them to achieve their maximum potential, there is more to come.

The Electromagnetic Spectrum

Electromagnetic radiation is constituted by radiation of all possible frequencies within the Electromagnetic Spectrum; divided into seven major categories: radio waves, microwaves, infra-red waves, visible light, ultra-violet rays, X-rays and gamma rays, in order of increasing frequency and decreasing wavelength. This radiation, more often than not, takes the form of waves, that propagate (travel) through space (vacuum) at the speed of light (c), and through other materials a bit slower.

Wavelength and frequency are but two defining properties of every wave. Wavelength, λ [lambda],  refers to the distance between two adjacent peaks. Or troughs. Or “2 points on a wave in phase with each other”, but we can look at that one later. This length is representative of the objects (or gaps between objects) around which the wave can manoeuvre itself. It is measured in metres (m).

Frequency, f, is the number of wavelengths that pass over a particular point in space in one second (1 s). In pronciple, ot respresents energy – the higher the frequency, the more energy is carried by the wave. It is measured in Hertz (Hz) or “per second”.

c, λ and f are related as such:

c = fλ

you will need this one so remember it!

As c is constant, f and λ are inversely proportional, meaning that high frequency waves generally have short wavelengths, and vice versa. One may also conclude from the fact that one of the units for frequency is “per second”, frequency is related to time as follows:

f = 1/T

where T is time, measured in seconds.

As for the uses of the different types of waves, I would point you either to the picture included in the previous post or the slightly more, er, legible one below. In these cases I believe images do the work better than words.

Electromagnetic Spectrum (Courtesy of Virginia University, clickable!)

Now, aside from me (and other people) telling you so, why would you believe all this? How can we separate waves in a visible manner? Well, try this: (adapted from TV show Backyard Science)

You will need a cardboard box (a shoe box will be fine), some 3D glasses (the ones sometimes used for watching 4D films, ironically), scissors, clear sellotape and different types of light, e.g torches, desk lamps, UV lights, and provided you take care, matches.

Cut the lenses out of the 3D glasses. On opposite sides of the box, draw around one lens, and cut out a lens-shaped hole. Use the tape to stick the lenses on the box, such that the holes are covered. Shine each light at one of the lenses whilst looking through the box with the other lens. What do you see?

Note: The 3D glasses refract (bend) the different wavelengths by different angles, so you should be able to see the colours that make up each light.

Back to the Sun

I admit to having teetered towards the social science domain in the last post, and sincerely apologise. We had better get cracking with the good stuff.

Let us start from the Sun, a mind boggling ball of plasma (think of it as hot gas for the moment, although not the kind to be taken lightly), constantly spewing energy in a radial fashion (meaning from its centre outwards, in every direction), primarily in the form of heat and light. This energy travels through space, and on its journey, smacks the Earth in the face. Well, it whichever half of Earth’s face that happens to be pointed towards the Sun at that particular moment.

Disection of the Sun (clickable! from HowStuffWorks)

You have very possibly been told that the Sun is responsible for a vast number of natural phenomena observable on our planet, such as photosynthesis, rainbows, and the weather. Of these examples, both photosynthesis and the weather are the results of energy transfers (rainbows are an optical phenomenon); but if the Sun is so far away (namely 1.50×10¹¹ metres to 3 significant figures, also known as an astronomical unit), how does the energy get here? And then how does it spread itself out to perform its duties?

Let us start with how it gets here. More often than not, energy travels far distances in the form of radiation, as waves. The Sun emits radiation across the whole electromagnetic spectrum; these waves all travel through the vacuum of space at the speed of light, (as mentioned in the entry with all the experiments – how long does it take for the Sun’s radiation to reach Earth? See footnotes for the answer). This also works, for example when you are sunbathing; you do not have to be touching the Sun in order to get burnt, so always wear suitable clothing and SPF.

The electromagnetic spectrum (by California Berkeley)

Once the radiation has made its way onto our doorstep, and impacted on the surface, conduction takes over. Somewhat. Conduction is the transfer of (principally) heat from a hot object to a cooler object when they are touching. These objects can be the air and the ground, the sea and the surrounding land, or the hob plate and saucepan sitting on top of it, as well as the soup in the pan! This is why you keep your fingers away from things like hot irons (speaking from experience here).

Conduction - the hand is holding a metal rod; the arrow shows direction of heat flow (from http://www.antonine-education.co.uk/)

An interesting thing happens when the heat reaches large quantities of water, like in the oceans. The heat evaporates the water near the top, turning it into warm water vapour, which rises up through the air, above the cool air below. This is called convection, and can result in anything between clouds and hurricanes (see pictures below).

Dry and moist convection (from ABC Channel 13 News Blog)

Test for convection

Here is a cool demonstration of convection that you can carry out at home. You will need two bottles with identical openings at the top, a hot, coloured, liquid(e.g tea) and a cold, clear, liquid(e.g. water).

Fill both bottles to the top with each of the liquids. Carefully turn the cold bottle of liquid upside down and place on top of the bottle of hot liquid so that the two liquids are in contact and nothing is spilling out. What happens to the system (= the bottles and the liquids)? Tell me in a comment, and see you next time!

Note: It takes approxiamtely 500 seconds, or about 8 minutes, for the Sun’s energy to reach the Earth.

A Big Picture of the Curriculum…

… applies to England and Wales, I believe. Have a look for yourself:

The Curriculum according to the QCA

Nice and colourful, is it not?

I am unsure as to how many people actually care to look at it, and not simply take it for granted that the government’s idea of a sound education is concordant with their own. For one, note that Mathematics is cited under “Personal, social and emotional development”. I am not sure how many pupils would disagree with that particular statement.

As I get on with blogging, I do find that research sometimes brings me information I did not wish to know, e.g. the fact that one of the GCSE Science exams is now composed of multiple choice questions, and contains considerable quantities of social science and economics. So amidst the unpleasantries, I was intrigued to be presented with “The Big Picture”. What it is all about. And it is rather lovely I say – all about making sure young children grow up to be happy, healthy and conscientious adults. Then, as we progress through the stages of education we may not feel that being at school makes us particularly happy or healthy; and I feel that the increasing focus on society as a whole -through education- may not be completely beneficial. Pupils are shown what society is like today, and sometimes asked how they would change it for the better (from their point of view), which is a good idea, but I still prefer the old method where each subject is taught in its pure form, which allows young people to use that knowledge to create a completely new world. It may be far fetched, but children should be able to dream without having to mind reality.