• scissors
    May 14th, 2013ImogenUncategorized

    Wonderful Water Thing #1

    From my previous post, you may have realised that my house isn’t that warm. The place I’m living in was built in the 18th Century and isn’t exactly airtight, but water vapour from cooking and breathing still builds up inside the house. The thing is, cooler air holds less water, so when the air reaches a cooler surface, water falls out of the air and sticks to the cold surface. This appears as condensation on windows.

    This is how clouds are made too. Air gets cooler as you get further away from ground level, so at a certain distance from the ground the air will reach a temperature where it can no longer hold the water vapour dissolved in the air, and the bits of water that had been dispersed in the air start to stick together and reflect light. This makes them appear white. The height at which this happens is known as the cloud base. Window condensation is basically a cloud stuck to your window, so that’s actually pretty exciting.

    Watery Wonderful Thing #2

    I was driving home from work today and there was a humungous rainstorm. I was seriously glad I was not on my bicycle, or I think I would have dissolved in it. The sunshine with the rain made a rainbow pop up but it was so low in the sky I could see both ends through my windscreen. This realisation did nothing for my concentration. The thought of pots of gold hiding on the golf course is enough to make a girl lose her hubcap.
    It turns out that the height a rainbow will occur at is linked to the time of day. A rainbow is essentially a circle, and the circle’s centre is at the opposite point in the sky from the sun. At sunrise or sunset, this point will be on the horizon, so the rainbow will be at its highest. As the sun rises, the bow’s centre gets lower so that its centre is below the horizon and to us it looks smaller. The rainbow always appears to have the same radius of 42˚, so when the sun is 42˚ high only the top of the rainbow is visible over the horizon.

    I say appears, because the rainbow is not fixed in space, as you will know if you’ve ever tried to reach the end of one. It really is just a mirage, you can never get any closer to it because it’s not really there.

    Wonderful Watery Whatsit #3

    The third amazing thing is very simple and I noticed it when I was soaking my rice this evening in a few centimetres of water (this is pretty low tech). I was moving the saucepan back and forth waiting for the kettle to boil and I realised that as the water moved, the base of the saucepan appeared to be rocking up and down.

    Rainbow over the park

    Today's rainbow from the same window

    As the bigger mass of water came over a spot, the water refracted the light more. The effect of this is make the distance between us and the object appear smaller, so the base of the saucepan appears closer the more water is over it. As the water rocks away the light is refracted less and the base appears further away again. Wibbly wobbly saucepan! It’s like magic. I recommend a big saucepan for the best effect.

    There are like a zillion more amazing things that water does. This is just the tip of the iceberg (ahahaha).

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  • scissors
    January 9th, 2013ImogenUncategorized

    Hello science fans. Now that I have graduated University and become a Real Person With a Job and Everything, I have become best friends with my hot water bottle. To the extent I mention it so often in texts that it has become abbreviated to HWB. There is, I am discovering, an art to filling a hot water bottle so that it provides enough heat for enough time without being too unbearably hot.

    The problem is, I always get distracted and don’t stop the kettle before it boils. Boiling water makes for an HWB that’s too hot under the duvet. But when I add cold water to the near-boiling water, this just feels a bit wrong. Basically, I lied when I said this is an art. It’s not, it’s a science, and here’s why.

    Let’s say that instead of water in my container, I have identical rocks. Each rock has a hotness score or 0-10 where 0 is room temperature (the temperature all rocks are going to cool to eventually) and 10 is super duper hot. A group of rocks collectively loses one hotness point per minute as it cools. Par example…

    Scenario 1: I use 10 rocks each of hotness 1 so my container is at temperature 1. I have 10 hotness points and this keeps me warm for 10 minutes. Hmm not good enough.

    Scenario 2: I use 5 rocks each of hotness 10.. This gives me a total of 5×10=50 hotness points so my container keeps me hot for 50 minutes. A container which starts at hotness 10 is too warm though

    Scenario 3: As a compromise, I use 10 rocks of hotness 5. This equals the same amount of hotness points as before, so keeps me warm for the same amount of time as Scenario 2 but the starting average temperature of 5 is perfect!

    Scenario 4: I’m so pleased with my success from Scenario 3 that I forget the rest of my rocks are on the fire and I come back to find they are now all 10 hotness points. Oh no! Too hot! What to do? I need 50 hotness points and a starting temperature of 5 for optimum bed cosiness. If I take 5 rocks of hotness 10 from the fire and add 5 rocks of 0 hotness (room temperature) then the average (overall) temperature is now (10+10+0+0)/4=5 hotness, and I have 50

    hotness points to keep me warm for ages! Hooray!

    This means that if I use near-boiling water and then add cold, it will give me a hot water bottle which is not too hot, which will last for longer!

    You are welcome.

     

    Not 42, just HWB
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  • scissors
    March 1st, 2012ImogenUncategorized

    Noble, gaseous air. Can’t live without it, can’t walk over it. If you’re not an Olympic swimmer then you probably spend most of your waking hours moving through air. Therefore, as well as serving a perfunctory functional purpose, a bath can be a bit of respite. A change of scene- or state, if you will. However, next time you have a bath, there’s no need to just sit there! Did you know that there is a whole host of micro-experiments you can try out, all from the comfort of your lavender scented water? Here are my top 3 favourites.

    1. Wave Interference

    Unless you are some sort of bath-drawing pro, there’s always some essential water mixing to be performed. This is a perfect opportunity to make something constructive. Or destructive, if you so wish. Make some waves travel down the bath then watch as they are reflected by the end of the bath and travel back on themselves. Where two peaks intersect you will get constructive interference and the wave will be bigger and splashier. If a peak and a trough meet then they will cancel each other out and you’ll get a ‘node’, or flatness.

    This is exactly how noise cancelling headphones work: the headphones listen to the ambient noise around you and play you a sound wave that is the exact opposite to the noise. The ambient sounds are cancelled out by the new wave and so you don’t hear it. This is why these devices work better for environments with constant noise levels- when you are on an aeroplane, for instance.

    2. Manual Airfoil

    Technically a waterfoil, but that sounds like a duck or something. If you make a cupped shape with your hand under the water and sweep it along your leg, you will feel a suction pulling your palm towards your lallies. This works best if you hold your hand as close as possible to your leg without actually touching it.

    Your hand is moving through the water like the wing of an aeroplane moves through the air. As the water moves over the curved back of your hand it has to travel faster than it does under your flat palm. The slow moving water under your hand creates a region of lower pressure, effectively sucking your hand in that direction. So really, planes don’t fly, they’re just suckers.

     self portrait

    3. Living on Jupiter

    Ok so you’ve made waves, swooshed your hands around, splashed lots of water on the floor, and maybe got a bit cleaner too. Before you turn into a complete prune it’s time to get out, but you’re just so relaxed and comfy. Instead of arising abruptly and possible getting a head rush and falling and hitting your head on the sink and having a brain haemorrhage (don’t say I didn’t warn you), try number 3 instead. Lie in your bath and take the plug out. As the water line drops further, you will start to feel strangely heavy. Your muscles have had a bit of a holiday, aided by the buoyancy of the water. Now the water’s gone there is no upthrust, only a force of approximately 1 Newton per Kilo pulling you towards the centre of the Earth. Now, don’t you feel like you’ve just come back from the moon?

     

    If you like to take some refreshment at bathtime then be sure to check out my other blog post Slurpy Bath Tea, it’s essential reading on the topic.

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  • scissors
    January 15th, 2012ImogenUncategorized

    This term I have been enjoying the work for the module “Communication of Scientific Ideas”. One of the pieces of coursework calls for a scientific radio show. I had the pleasure of working with Jennifer Mahoney, Tessa Jones and Amy Yau and we had a great time making it. I think you will agree that Jen has a beautiful radio voice and made an excellent host.

    If you attend carefully you may hear me referred to as ‘Dr’ Imogen House. Alas I have not completed a PhD, I was merely masquerading as a researcher, borrowing the story of Clare Elwell. Clare is a Professor in my home department and I have done another couple of pieces of work based on the interview she gave me a couple of months ago about her fascinating work. Stay tuned for further updates.
    Our show- “The Pink Room” has two fascinating interviews with two up-and-coming lady scientists, and an update on all the latest (a couple of months ago) science news. We hope you enjoy it!

    The Pink Room – episode 1

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  • scissors
    August 4th, 2011ImogenUncategorized

    This week’s science question comes from my dear mama. She asks “Why do I dribble when I sip my champagne in the bath?”.

    Just for clarification, the champagne is wishful thinking and my mum is much more likely to be drinking tea. Either way, why is it that one who knows much better can’t help getting tannins in her bathwater?

    The answer is surface tension. Alike molecules­­ attract and hold on to each other via cohesion. H20 is a polar molecule, so it has both a positive and negative end which means that one H20 can turn around and attract another. Water molecules form a linked surface layer which tries to resist attempts at breaking it. You can see this in drops of water clinging together on a hard surface, or that well known systematic error-source, the meniscus (for future reference, one must always measure from the bottom of the meniscus). Rivulets of water running down your window follow the path of least resistance, and this means the path that is already wet. Drinking when your face is wet elicits the same effect: water does not retain its surface tension and flow exactly where it is directed, but follows the path which has already been laid by your bubbly beard experiments.Minimise those errors!

    The solution I would suggest to my mum as she gets tipsy on her PG is either 1) dry thine face or 2) use a straw. Anything else is likely to result in a tragic loss of beverage.

     

    Is there a scientific issue you’re curious about? Is there something you wish you could hear explained simply? If so, drop me a line at [email protected], on twitter via @imogenhouse or using the contact form, and I’ll break it down for you so you need never lack the answer again.

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  • scissors
    March 29th, 2011ImogenUncategorized

    Tea Vortex

    Sometimes it is easy to find anything more interesting than the work you should be getting on with. This morning I took a break from revision to make some tea. I had to use powdered milk but sadly it 1) refused to dissolve properly, and 2) tastes weird, so I didn’t drink the resulting brew and it remains on my desk. As my mind wandered from the mysteries of dielectric materials in capacitors I developed a fascination with stirring my now-cold tea.

    By stirring the tea and then placing the spoon perpendicular to the edge of the cup I can create a mini vortex. Milk particles orbiting in the vortex have more speed than those which continue to do a full circuit of the mug. This is because they seek to conserve their angular momentum. Angular momentum is equal to the product of the radius of the circle, the mass of the particle and its velocity. The mass does not change so as the radius decreases, the velocity must increase in order to keep the angular momentum the same.

    What is concerning is that this is only my second day of revision and my exams are still 6 weeks away. I dread to think what will be entertaining me in the weeks to come. My reflection in a spoon perhaps? Perfecting my “r” rolling? Actually between sentences I am already experimenting with rotating on my swivel chair by waving my arms around like an over-intent cheerleader.

    Whatever keeps us sane, eh? I suppose I’d better get back to work.

    Oh look it’s almost lunchtime!

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  • scissors
    March 24th, 2011ImogenUncategorized

    They say that there is no such thing as bad weather, only inappropriate clothing. However, as a carefree young girl-about-town (read: impoverished student with small handbag) I happened to be tragically ill-prepared one day when the weather took a turn for the worse. As luck would have it on this drizzly day I had cycled into university. In order to retain my right to scoff at fair-weather-cyclists I felt obliged to brave the precipitation, mac or no mac and so I set off on my merry way. At least, it might have been merry if I had worn my gloves.

    For some time I was perplexed as to why my hands were getting so nippy. They were disproportionately chilly compared to the rest of my extremities but I couldn’t work out why. It was only when I got back to my house and was fumbling with the bike lock I realised that there was a very simple reason: it all comes down to evaporation.


    Mastering evaporation. (safely)

    There are two main reasons for this chilling effect (chilling where things get colder, that is. Physics is nothing scary). These are firstly, the varying energies of different molecular states and secondly, the law of diffusion. Here’s how they work.

    Molecules (with a few exceptions) are found bound in one of three states: solids, liquids and gases. A gas molecule has more energy than a liquid molecule, which in turn has more energy than a solid. This energy takes the form of tiny molecular vibrations – generally measured as heat. As temperature increases the individual molecules gain more energy and so start to vibrate more vivaciously. As vibrations grow the molecules will gradually break bonds to their neighbours. This is why as you go from solid to liquid to gas the substance becomes less rigid and more free-flowing.

    When I was learning about molecular states at school we did a practical in the playground, swinging about hanging onto each others’ elbows. As our class’s “heat” increased we were ordered to progressively let go of each other and observed how much further we could rampage as a result. If you feel a desire to experience this yourself I suggest experimenting by grasping on to a friend while you are a) standing on plastic bags, b) standing on skateboards or c) at the mercy of a small footloose child. The less random movement occurring, the greater your chances of remaining bound to your fellow molecule.

    Particles always diffuse from an area of high concentration to low concentration. This is a fundamental rule in physics, and explains why the smell of burnt toast manages to permeate every room in the house. Water on a surface is of a higher concentration than water vapour suspended in the air, so eventually the surface will “dry out” as all the water evaporates in an attempt to even out the concentrations. The surface will also be left cooler, as we have seen before. Finally, moving air increases the rate of evaporation because the concentration in the air is kept much lower than at the surface as evaporated molecules are consistently removed.

    In order to escape from a liquid and become an unconstrained gas particle, a water molecule needs to gain some energy from the liquid first. So how does this relate to my cold hands? As the tiny water droplets left my skin they took some energy with them, making my skin feel cool (because it’s just lost some heat energy). My skin then had to burn stored energy (from food) to generate more heat to bring it back up to temperature – I wouldn’t recommend hypothermia as a great weight-loss method though.

    Instinctively, we already know all this, that’s why everyone blows on soup. By huffing and puffing you increase the rate of evaporation. The greater number of particles escaping the surface means the liquid loses heat energy. This makes your food (/drink, I’m never quite sure with soup) less likely to burn your tongue.

    So what’s a similar effect? A fan in a closed room will not actually cool the room since it’s only moving air around (if anything, it’s heating the room up by creating heat via friction in its moving parts). However, if it’s blowing air at you, you will feel less hot as the moisture on your fevered brow evaporates.

    And this is why my hands were so very chilly in the wind and rain. What I really needed was a good pair of waterproof gloves to keep me warm. In fact, I have some such gloves at my disposal, but I forgot them that fateful day. Maybe what I really need is a better memory, but unfortunately neurology isn’t my speciality. In fact, if anyone would like to break down the science of remembering things for me, I would always love to learn more.

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  • scissors
    February 8th, 2011ImogenUncategorized

    In My Humble Opinion, Ultrasound is very cool. It is not as amazing to look at as MRI, nor as potentially lethal as X-Rays, but it can be used for a lot of diagnostic purposes. Many of us may remember ultrasound imaging from that grainy black and white image someone showed you excitedly as you tried to work out what it was. Or if you are like me and have not had any pregnant friends, remember that scene in Friends? This is because pregnant women on the NHS are currently offered at least 2 sonograms during their pregnancy in order to calculate the age of the foetus and to check it is growing healthily. Therefore this is the way in which we are most aware the way of using high-frequency sound to image inside the body.

    However, the applications are much broader. The first ultrasound machines were basically modified flaw detectors. Flaw detectors were used by ship builders to detect faults in the metal hulls of boats. The sound waves travel through the metal and are reflected by the air which fills cracks and imperfections. The connection was made by Ian Donald, Regius Professor of Midwifery at the University of Glasgow (Regius means that the post was originally created by a monarch and each appointment must be approved by the crown. This position was founded in 1815 by King George III). He was a keen sailor and became familiar with Sonar and Radar while serving in the RAF in the Second World War. Sonar was developed after the sinking if the Titanic and used sound waves to probe several miles of ocean. Any reflected sound indicated the presence of a possible ship-sinking object. Radar works in a similar way but using radio waves. It was Douglas who first brought ultrasound into the hospital to peek at babies in utero. Many developments then followed to develop the machines we use today, which have a mobile computing and display unit and a small probe on a flexible arm. The first machines required the examinee to sit in water bath so that the probe could achieve a good contact. This is because however hard you press a plain old probe against the skin; some air will still exist where the two meet. The air will reflect the ultrasound waves before they even get into the patient so that you will just get a useless fuzzy image. The modern ultrasound gel is water based (easier to remove than oil-based formulations) and forms a perfect air-free join for the sound waves to pass through before and after the body. It’s true what everyone says though, it does feel very cold when they put it on.

    Unlike X-rays, ultrasound does not fall under the classification of “Ionising Radiation”. That means that when the waves pass through your body they will not cause damage and so their use as a diagnostic tool does not need to be restricted in the same way. In light of this, ultrasound is frequently used to view active functions inside the body, in particular the function of the heart. A physician may employ ultrasound to view the action of particular heart valves if he suspects that the heart is not pumping correctly. By examining arteries to the brain and lower body it is possible to assess the risk of getting a stroke or blood clot by looking for plaque in these important vessels. During the first three months of a foetus’s life, the cells are dividing more rapidly than at any other point in its existence. More cell divisions mean more opportunities for things to go wrong, so to X-ray a baby at this point would be very hazardous. Therefore, non-ionising radiation such as Ultrasound is invaluable to check up on the baby without harming it. Recently, scientists have developed a pre-natal test for Down Syndrome which does not require an extraction of cells from the uterus. This is good because tests such as amniocentesis or chronic villus sampling (both of which use a needle to take cells from the amniotic fluid or placenta respectively) carry a risk of miscarriage. In the new technique, a ultrasonographer examines the nasal bone since babies with Down Syndrome tend to have a flatter bridge of the nose and almost nonexistent nasal bone. A test for “nuchal translucency” can also estimate the thickness of the skin at the back of the neck using a high-frequency ultrasound. A higher than normal thickness can indicate a genetic abnormality.

    However, ultrasound can be used for quite different purposes. Some anti-abortion politicians in certain states in America (such as Montana) think that women seeking a termination should have to have an ultrasound scan and listen to the foetus’s heartbeat for up to one hour before making a final decision. Abortion is a highly controversial issue and if this scan was compulsory then it would not fail to emotionally affect both the woman faced with this decision and the doctor forced by law to carry out the procedure. Some very interesting moral questions are raised, but this is not a political blog, so I won’t say more on the matter.

    AND SO to haul this post back from grim opinion-ism , I would like to draw your attention to this lovely little story I read the other day about the amusing pictures ultrasound can capture. Aaaaaah.

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