Explore Microbes at Home
About replace material of this project
Dear
Dr.Michelle
I got a microbes kit but I have done many projects and the easygels ran off. Is
there any other material that I can use?
Can I use gelatin? But if I use gelatin, how can I know whether there is
bacteria? Is there anything that I can stain them?
Please reply as soon as possible, Thankyou
sciangel
Re: About replace material of this project
If you use
gelatin, you will need to add a nutritive substance like a beef or chicken
bouillon cube and sugar. There are various recipes online. However many
bacteria poduce enzymes that can dissolve and liquify gelatin, which is made of
protein itself. So agar is better. It is not subject to this problem. You do
not need to stain the bacteria to see them. They will appear as white or
yellowish dots on the surface.
Dr. Michelle
Re: About replace material of this project
You can now
buy a replacement set of plates and media at:
http://www.1shoppingcart.com/SecureCart/SecureCart.aspx?mid=FA8D15FC-AE8B-4432-A0F0-3AA8501B2F48&pid=339593a73c72dc242bb75ff586d7384a&bn=1
If the bacteria keep increasing, is it just growing, or is i
If the bacteria keep increasing, is it just growing, or is it the original bacteria that was in the water?
Re: If the bacteria keep increasing, is it just growing, or is i
by DrMichelle on Wed Aug 26, 2009 3:59 pm
E. coli and
other coliforms grow very rapidly when compared to most other bacteria, so they
generally appear in the plate first. Any colonies that appear after 48 hours
should be disregarded.
Second, if you are incubating at lower temperature ("room temp"), the
colonies will not appear as soon. In this case, you should wait until you are
seeing the first colored colonies and then give at least another 18-20 hours
for further growth and development of color before counting the results.
Colonies that do not grow past a pin point size (less than 0.25 mm) within 48
hrs at 35 C. should not be counted without further testing, especially if they
were late showing up. An exception to this rule is if there are so many
colonies in the plate that it is covered with colonies very close together.
Such a plate can even look like it doesnŐt have any colonies at all and just
have a pink or bluish cast throughout the whole plate.
Colonies growing down in the solid medium will be smaller than those growing on
the surface and surface colonies generally are paler in color. Also, if
colonies are crowded close to each other on/in the medium, they will not grow
as large.
Rarely, there may be present a large colored spot growing on the surface or under
the medium on the plate. This is usually the result of a colony growing at the
edge of the plate and down under the medium where there may be excessive
moisture where it can spread, and it should be counted as only one colony
forming unit.
Why do the bacteria appear red?
Why do the bacteria appear red?
Suzan
There is a
Tetrazolium salt added to the petri dish that reacts with an enzyme made only by
living cells, that turns the salt pink.
Dr. Michelle
What is the Easygel made of?
Dr.
Michelle,
What is the Easygel made of?
Erica
Re: What is the Easygel made of?
Erica,
Easygel is a pectin based bacterial growth media that gels when it comes in
contact with the specially treated petri dish.
Dr. Michelle
Delay between collection and plating
Dear Dr.
Shawn,
I am collecting a sample at the local animal shelter to collect saliva. It
takes 45 minutes to drive back home. What would be the most efficient way to
collect the sample: dip the applicator into the easygel & then pour into
petri dish there or just leave it in the easygel bottle (w/the lid securely
back on) & pour it into the petri dish when we get back home?
Thanks for your help!!!
--
Leslie Anne
Re: delay between collection and plating
Leslie,
That's a good question. If you have access to a clean flat surface, you could
pour the plates there. However, it takes about 45 minutes for the gel to
solidify once it is in the plates and so you really don't want to move them for
at least this long, once they are poured.
I think it would be safer to dip the applicator into the easygel bottle, swish
it around, then remove it before promptly capping the bottle. You can then pour
the liquid into the plates when you get home. The Easygel will remain a liquid
until it's combined with the plate, which is treated at the bottom. If you want
to make sure no bacterial growth occurs until you get home, you can put your
bottles into a cooler.
Let us know how your experiment goes!
Dr. Michelle
Some question about 'microbe incubator'
Dear Dr.
Michelle,
I am the one who ask a question here last time! The problem finally was solved
as I find that there are still 5 easygel left. Anyway, thanks your support.
This time, I have some question about the 'microbe incubator' in the
instruction booklet! I don't quite understand how to do that...... Also, I want
to ask
if I can get a copy of the instruction booklet, as I have make some 'dirt' on
mine...And I am not a member of scifair.org as this kit is presented from my
friends...
If you can, please send it to my email, i'll keep it well! Thanks
Yours,
Angel
Is Easygel safe?
Is easygel safe?
Re: Is Easygel safe?
Yes, it's
very safe. It's just food for bacteria and starts off
completely sterile. I wouldn't recommend drinking it however.
Dr. Michelle
Microbes not growing
We tested a
toilet seat, money and a cell phone and only one spot is
growing
on one dish after 48 hours! The petri dishes are in a drawer in a
bedroom
at a fairly constant temp.
Help!
We tested 1" square areas of each.
Thanks,
Brigette
Re: Microbes not growing
You might
give your dishes one more day because some bacteria take longer
than others. However, I think that you have discovered
that these surfaces really DON'T contain that many bacteria. In fact some of
the places people would think would be the dirtiest are not. Studies have shown
that toilet seats, contrary to what most people would think, are one
of the cleanest places. Bacteria do not live for long on many
surfaces, especially if they are dry. Places
that are likely to contain a lot more bacteria are kitchen
surfaces, bathroom counters and faucets, dish rags, refrigerator
interior surfaces, and human hands, any place that is not left
untouched for very long. You might want to test some of thes surfaces to
round out your experiment. Try a person's hand (before washing) or
some areas around your kitchen sink.
I believe your experiment has worked perfectly.
Sincerely,
Dr. Michelle
Re: Microbes not growing
Hello,
We do have a lot more growth at the 3-4 day mark. Just today the little red
specks appeared and I realized what we were seeing may not even be what we
are supposed to report. We had one red spot early on, that was red on the
underneath and was white an fuzzy on the other side. Most of the petri
dishes have white spots. I was rereading the info and found that we are to
only count the red spots...is that so? And if so, what are the other white
spots? We were so excited that they were growing, and now we realize that
they aren't red!
SO, just tonight I noticed what looked like red marker spots that appeared
today. Is THAT what we are supposed to report? And, how long is too long
to grow a sample. Is there a cut off?
Thanks,
Brigette
Re: Microbes not growing
Hi
Brigette,
The colonies of bacteria should be very tiny red dots and grow to be no larger
than the size of pin or pencil head.
White spots are most likely mold.
Dr. Michelle
Re: Microbes not growing
Thanks! By
the way, the white spots are moldy spots. I am guessing that
they are dead or non-viable cells...I will include a couple of pictures.
Our project is due Tuesday morning...I think that we are okay because the
red dots finally showed up!!!!!!!! They must be weak strains, because they
took days to form. We did what you said and rounded it off with unwashed
hands...wow, those grew in 24 hours, must be srong strains!
The 3 petri dishes with labels had those moldy spots early on, then the red
dots appeared,(this pic was at 96 hours). There are 2 red dots on the cell
phone and one on the toilet seat. There were none on the dollar bill,
probably because it was not in circulation for months. The dishes labeled L
and R are of the dirty hands and really did not grow the moldy spots (this
pic was around at 65 hours).
Thanks,
Brigette
Attachments
Images of Dishes2.jpg (53.35 KiB) Viewed 600 times
Images of Dishes1.jpg (56.9 KiB) Viewed 602 times
Testing mouths for bacteria
Hi there...
My son and I are working on his science fair project... We also recently
received your "Home Microbiology" kit...
In a nutshell, we are going to examine whether various mouthrinses can/will reduce
the number of germs in our mouths following their use. The protocol is to have
a "control" sample taken without the use of a mouthrinse, plus 2-3
samples taken following the use of different mouthrinses on 2-3 other
mornings... We plan on using the mouthrinse for 1 minute, swabbing the oral
mucosa, and then "inoculating" the EasyGel with the swab before
pouring the EasyGel into the petri dish.
Will we be fine simply swabbing the oral mucosa with the dry/sterile swab and
then inserting the swab into a bottle of EasyGel to inoculate it? Or should the
swab the "dampened" with something before swabbing the tissues of the
mouth?
Thanks...
Mike
Re: Testing mouths for bacteria
Mike,
Yes, just use the dry sterile swab to swipe inside the mouth. They'll be plenty
of moisture there. You only need to dampen the swab when you are swiping a dry
surface. Although the Easygel media is not hazardous, it's not a good idea to
put it inside your mouth.
Dr. Michelle
Extract DNA at Home
DNA fingerprinting
by DrMichelle on Mon Feb 23, 2009 4:17 pm
Hi,
We downloaded you science fair information on electrophoresis. We were
wondering if DNA fingerprinting is what is happening during the electrophoresis
process?
Thanks,
The Sutherlands
Re: DNA fingerprinting
Hi,
No, the typical procedure for DNA fingerprinting involves chopping up genomic
DNA (the DNA from a cell's nucleus) at key places in the DNA sequence using
enzymes called restriction enzymes. One does this to make it possible to look
for small length differences in these DNA segments that naturally occur in
different people in the population. These pieces can then be sorted by size and
analyzed using a number of different methods.
Electrophoresis is the general procedure of using the naturally occurring
charge on various molecules; dyes, proteins, DNA, etc. in order to sort them by
size. A voltage is applied across the gel and your samples placed at one end.
The gel is made of a special material, usually agarose or some other polymer,
which forms a uniform matrix that impedes the motion of the molecules. Longer
ones take more time to get through the matrix than shorter ones just like it
would take longer for large impurities to make it through a column of sand than
it would for water to get through. Since it takes longer for large molecules to
get through the gel than shorter ones, this method can be used to sort
molecules by size, including DNA.
Although electrophoresis is sometimes used to analyze the size of the DNA
segments from DNA fingerprinting, discerning the small differences in fragment
size requires techniques and materials currently beyond what be used at home.
Hope this helps.
Dr. Michelle
Extracting human DNA
Dr. Shawn,
Regarding my CSI order. I am very excited to receive it. I am ordering it for a
student of mine who is obsessed with doing her science fair project on DNA
fingerprinting. She was hoping she could work with hair. (she wanted to see if
there is a difference between identical twins, fraturnal twins , ordinary
siblings, and non family members.) We were having a hard time getting a recipe
for Hair DNA extraction.)
Does it have materials and info for DNA extraction from hair?
Regina
Re: Extracting DNA from humans
Dear
Regina,
Delighted in your interest with our kit--however.... You can not do DNA
fingerprinting this this or any other commercially available kit. The chemicals
required to do this work are dangerous and expensive, and the method of
separating the strands of DNA is also expensive and uses dangerous chemicals.
So you won't find a kit that will enable you to test one human's DNA against
another that is intended for science fair students.
You don't want to extract DNA from hair because only the living cells at the
root of the hair contain DNA, so you would need a lot of hair to get enough DNA
to see. Scientists use a method called Polymerase Chain Reaction or PCR to
amplify small amounts of DNA in the amounts that can be analyzed. This takes
special equipment and enzymes. The kit extracts DNA from living plants and from
animal tissue, like things you find in your produce and meat department at your
store.
That being said, our kit will allow your student to extract DNA hundreds of
times from all kinds of things in the living world and to do a number of
experiments with it.
Yours for great science,
Dr. Shawn
DNA from banana in different states of ripeness
Dear Sir:
My son is doing a science project using your DNA Kit and I have a few questions
so I will know if his hypothesis will be correct or not and what a proper
conclusion can be written. He extracted DNA from an underripe, ripe, and
overripe banana. His hypothesis states that he thinks the ripe banana will
contain the most extractable and measurable DNA. Should it?
Also, how do you measure the amount of DNA -is it the blue band only or what
lies in between. We are not sure. It looks like 3 ml for the underripe banana,
2 ml for the ripe banana and 1 ml for the overripe banana. Do these
measurements sound correct to you.
Please advise as soon as possible. Thank you.
Re: DNA from banana in different states of ripeness
There are
several possibilities for why the quantity of DNA extracted will be different
for fruit in different states of ripeness.
One reason is that the density of cells could be higher for the fruit in
various states of ripeness. In other words, more cells for a given volume of
fruit gives you more DNA. This is because, the amount of DNA in the nucleus in
a given cell type will be exactly the same for all its cells. If a fruit's
cells are really big because they contain a lot of water or other stuff, not as
many cells will fit into a given space, and so you'll have less DNA.
Another reason could be that the ability to get the DNA out of the cells
changes in each of the different states of ripeness. It could be that it's
harder to get the DNA out of underipe cells, for example because they have
thicker cell walls.
A reason why ripe fruit would give you less DNA would be that in very ripe
fruit, many enzymes are released during the ripening process which can break
down the proteins and DNA in the cells.
There can be other reasons as well. When scientists do experiments like this
they usually get more questions than answers and have to do more experiments to
answer the new questions. I would suggest that you give some of the different
reasons why you got the results that you did and then maybe suggest an
experiment that someone could do in the future to rule out one of these
hypotheses. I don't know the actual answer but you certainly have a reasonable
result and can report some good explanations. The DNA is stained blue so you
should measure the size of the blue band.
Dr. Michelle
Monitor Atmospheric Haze
AOT & spirit level
Hi
Michelle,
Does the industrial waste in the atmosphere increases the AOT than a clear
atmosphere?
When we measure the Sun intensity during the day, does the spirit level (LEVEL
INDICATOR ON SCALE) should be at the center all the time?
Sundar
Re: AOT & spirit level
Sundar,
Typical AOT values are around 0.45 in polluted cities and 0.3 in rural areas.
Yes, the AOT is higher with with more pollution in the atmosphere.
The spirit level is only supposed to be used when you are taking a reading of
the sun angle, not for a voltage reading.
Dr. Michelle
In our AOT formula, what does the constant 8660 represent
Hi Dr.
Michelle,
In our AOT formula, what does the constant 8660 represent?
Kayla, my daughter, has completed the whole AOT analysis and is not sure of the
constant "8660".
Let me know and regards.
Rolando
Re: In our AOT formula, what does the constant 8660 represent
As
described on page 15, Mathematics of Monitoring Haze, the constant 8660 is an
empirical factor that factors in Rayleigh scattering at the peak wavelength
detected by your green LED (525 nm).
An empirical factor means that it is a number that has simply been measured
from experiments, not derived from physics theory.
Rayleigh scattering is the scattering of light by tiny particles much smaller
than the wavelength of the light, in this case mostly gas particles in the
atmosphere. This scattering depends on the wavelength of the light.
The equation for the AOT that you are using is used to calculate how difficult
it is for the sun's light to pass through the atmosphere at the wavelengths
that your green LED detects, peaking at 525 nm. The part of the equation:
MP/8660 takes into consideration the amount of Rayleigh scattered light between
the sun and your device at those wavelengths detected by your LED.
Hope this helps,
Dr. Michelle
Measure the Interplanetary Magnetic Field
Data
1) What do
you think about your science project?
My 12 y/o eventually learned a lot, but I had to dust off my physics and
astronomy to help him understand what he was doing. I know that this was listed
as 14+ on the web site, but he wanted to give it a try. The instructions say
12+, and he kept pointing this out to me when I would remind him of what he was
tackling. Suggest you alter the printed instructions to say 14+.
2) Are you having problems understanding any of the diagrams or the
instructions?
Our sensing magnet readily touched the CD case, impeding its rotation. It was
not clear from the instructions that you needed to rotate the CD case until the
magnet swings freely and orientates itself N/S, and that the nulling magnets
need be oriented along the N/S axis. On our initial trials we had the CD case
rotated perpendicular to N/S (!), so that the sensing magnet's rotation was
limited by the CD case. (It was able to oscillate slightly, fooling us into
thinking that we were detecting real IMF fluctuations.) Consequently, the
nulling magnet had to be quite close (~10 cm) before the sensing magnet violently
flipped around. We collected 2 days of data in which the device registered only
random noise before I figured out what was wrong.
3) Do you have all the parts you need?
Missing 1 pair of nitrile gloves, could have used 3-4 pair (little boys make a
mess)
4) What can do to improve this project?
A diagram showing the need to position the CD case to allow the sending magnet
to rotate freely and attain N/S orientation, and that the nulling magnets need
be positioned along the N/S axis passing through the sensing magnet, would have
saved us a lot of time and frustration.
I'm not sure how good our responses were. The example showed wonderful
correlation by an expert, presumably with rock steady table, collecting data in
the same area as a USGA magnetometer. The Virginia site was the closest to us,
at ~400 miles. I was not sure how much to attribute discrepancies to the
distance, our device, etc.
An example of a typical tracing would help, particularly showing how much noise
is created by simple vibrations from people living and moving about the house.
Also comments on how much variation to expect when you are not near a USGS
site.
We matched colors on the USGS site tracing to pick out the correct data. You
provided the website for the L1 satellite data, but I could not tell which
tracing to use from the lack of instruction documentation or web site
documentation. Evan a comparison of graphs like the USGS example would have
allowed me to match colors and graph notations.
5) What else can I do to make your science fair experience more successful and
enjoyable?
I am attaching a Power Point slide with our data from the third day of data
collection (the project was due the next day, so we were running short on
time). Does this represent a reasonable result?
Thanks,
jtk
Attachments
Slide2.jpg (35.37 KiB) Viewed 640 times
Slide4.jpg (30.18 KiB) Viewed 638 times
Re: Data
Joseph,
Thank you so much for your detailed responses. We will take these into
consideration for your next set of instructions. We have since changed our
instructions to say "14+" It is a challenging project.
I did look at your data and it looks very good. So glad you were able to set up
the webcam. You did see the same dip in the field that was seen at the USGS
location but not the peak. It is true that a difference in 400 miles could
explain some of the discrepancy. You can get a sense of this by comparing the
data between the different USGS locations. Also, I'm wondering if their might
have been something hindering the sensor magnet from swinging in that
direction.
I think he did a great job and I hope you'll let us know how he does in the
science fair.
Sincerely,
Dr. Michelle
Dependent and independent variables
Hi!
we ordered a science kit and will be taking the earth's magnetic pulse- however
question for you is---
How would we show variables? Any help you could give us would be great!
Thanks for your time!
Eddie
Re: dependent and independent variables
Examples of
possible variables are for example,
dependent: magnitude of interplanetary magnetic field from home build
magnetometer; independent: magnitude of magnetic field as measured by the USGS
professional ground instrument
dependent: magnitude of interplanetary magnetic field; independent: time of day
dependent: time delay in the interplanetary magnetic field of home built
instrument and NASA's instrument; independent: each peak and valley measured
dependent: strength of the magnetic field, as measured by the deflection of the
laser dot on your ruler on the wall (from the reflection on the sensor magnet);
independent: distance of your test magnet from the sensor magnet
Hope this helps.
Dr. Michelle
Laser pointer position and magnitude of magnetic field
Dr. Shawn,
I got the magnetic pulse experiment kit, made the magnetometer, and recorded
the results on the webcam for 7 hours in one day at one minute increments.
Your instructions were good, and It looks somewhat similar to the government's
findings.
But how does the Y axis (laser pointer position and in video pixels) translate
to numerical measurements of the magnetic field?
Also, in my science project, I must have a manipulated variable. I don't think
I have one. What would it be?
I received your instructions on how to construct the magnetometer, but I did
not get the "Complete Hypothesis to Conclusion Instructions" as
mentioned in your website that I was suppose to receive.
Maybe those instructions would help to understand what my variable was.
Please email me back with instructions and advise on what to do.
Thank you-Joshua
Re: laser pointer position and magnitude of magnetic field
by DrMichelle on Mon Feb 23, 2009 3:38 pm
Hi Annette,
To get a numerical value for the field you have to calibrate the device using
the calibration magnets that were included with the kit and the directions in
the instructions. OR... you can compare your device to the USGS instrument. If
that is calibrated, you can look at the same peak on your plot and their plot.
The USGS data will tell how the strength of the magnetic field that produced
that peak. The peak in your data will tell you how the displacement on your
instrument that corresponds to that size magnetic field. Since your device has
a linear response, you can easily calculate the magnetic field that corresponds
to any displacement. If the peak displacement was produced by 40 nanogauss,
then a displacement that was half as large would be correspond to a 20
nanogauss field and so on.
The manipulated variable... There is an independent variable--that's time. You
are monitoring how the magnetic field changes in time. But you aren't
manipulating the field. So there is no manipulated variable here. This is a
problem with school science projects, the teachers don't understand how science
gets done but they think they do. A great many scientific discoveries have been
made by finding a new way to shin a light into a dimly lit room just to see
what is there.
I suggest you show the teacher the results and discuss the need to have a
manipulated variable under the circumstances. Your project clearly deserves a
good grade and a chance to be judged by capable scientists.
One could measure the fall of with distance of the magnetic field of a small
magnet and this is also explained in the text. Then you are manipulating a
variable, the distance, and observing how the detector reacts. But this is so
boring compared to connecting oneself directly to the solar wind.
I hope this helps you.
Yours for great science,
Dr. Shawn
Field of the dipole magnet
Hello, I'm
back to bother you again.
1)The hypothesis my son picked was: "the field of the dipole magnet falls
as the square of the distance". The problem is I have no clue what that
means.
2) my son built the kit this weekend and has some questions:
a) as he pointed the beam onto the mirrored magnet, it reflected onto the wall
(and the ruler) - he noticed it was not a perfect pinpoint dot reflection on
the ruler - the reflection was vertical at the bottom and spread out at the
top.
Is this normal? is he doing something wrong?
b) approximately 2 minutes after the beam was reflecting on the ruler, he
noticed a shift from 15mm to 19mm for about 5 minutes - after that, it went
back to 13mm.
Is this correct/ does this really happen?
c) if the shift is correct, how many Tesla's is it - neither he nor I have any
idea how to measure
I will be home from 5:00 pm eastern at (305) 361-2882 and it would be really
helpful if you or Dr. Shawn could call as both my son and I will be here.
I need to make sure he understands before going forward.
Thank you very much.
Noris
Re: field of the dipole magnet
Dear Noris,
1) To square a number means to multiply the number by itself. Consider 1
squared. (in email we write this as 1^2, with the ^ symbol meaning "raised
to the power". In your son's report, he would write this as 1 followed by
the numeral 2 superscripted. 1^2 = 1 since 1 x 1 = 1 Similarly...
2^2 = 4
3^2 = 9
4^2 = 16
5^2 = 25
and so on.
So to say that the force falls as the square of the distance means that if you
double the distance between the two magnets, the force is only 1/4th as strong.
If you triple the distance between the force between the magnets is just 1/9th
as strong. If you increase the distance by a factor of 5, the force is only
1/25th as strong and so on. In other words the force (F) is proportional to 1 /
r^2. When we say that the force falls as the distance squared, we mean that it
follows relationship.
It's easy to test. Just measure the force at one distance, any distance you
like. (In your case you can simply place the test magnet say 10 centimeters
behind the magnetometer and measure the distance the spot moves along teh
wall.) Then double that distance (move the magnet to 20 centimeters) and
measure the force again. If the new force equals the first measurement divided
by four, you know that the force falls as one of the square of the distance.
That means, if the spot is only deflected one quarter the distance along the
ruler.
But what happens if that's not what you find? Suppose you double the distance
and the deflection is about 1/8th as much? Then the force doesn't follow the
square law. It must be following some other law. Consider this
2 x 2 x 2 = 2^3 = 8
3^3 = 27
4^3 = 64
So, if the force falls as the distance cubed, then if you triple the distance
the force will be only 1/27th as strong.
The way to do this experiment therefore is to measure the deflection for say
ten distances from say 10 centimeters to 50 centimeters. If you assume the
square law force, and you measure the deflection at say 10 centimeters, then
it's easy to predict what the force should be at each of the other distances.
The equation is the following.
deflection = deflection at 10 centimeters x (10 centimeters / distance)^2.
In words, for each measurement you make at some distance, you divide 10 by the
distance, then square the result. Then you multiply that result by whatever
deflection you measured at when the test magnet was 10 centimeters away from
the sense magnets. You can then plot these numbers on a graph, and then connect
the lines with a smooth curve. Did your data fall along that curve? If so, then
you have proven that the force between two magnets falls as the square of the
distance between them,
What if the deflections do not follow the curve? Then you need to try another
power law. I suggest you try the cube law. Again, if you measure the deflection
at one distance you can predict what the deflection should be at all other
distances. The equation is almost exactly the same as the last one, except you
cube the ratio of the distances instead of square it. In other words:
deflection = deflection at 10 centimeters x ( 10 centimeters / distance)^3
BTW: In your report, write the equation this way: D = D(10 cm) x (10 cm / d)^3
The D(10 cm) is shorthand for "deflection measured at 10
centimeters." This is the way a scientist would write it. And also you
make sure that you measures all distances in the same units, in this case
centimeters.
If you plot the points given by this equation you can see whether your actual
data matches the predicted data. If they do, you've proven that the magnetic
force actually falls off as 1 / r^3.
2) a) He is doing nothing wrong. The plastic mirror is not a perfect mirror, so
it does distort the spot. What matters is that you identify some feature on the
spot, (a dark area, a point of light or whatever) and always measure the
distance that that particular part of the spot moves.
b) YES!!! If you've zeroed the detector correctly, you are watching real shifts
in the earth's magnetic field. Most of these will be caused by the solar wind
smashing into the ionosphere.
c) You have to determine for yourself how many Teslas it is because the sense
magnets are all a little different. It will be in the range (assuming you have
zeroed your detector properly) of 10 nano-Tesla, or 10 billionths of a Tesla.
That's a fantastically tiny shift in the field!
I hope this helps clarify things. I can't call tonight because I have previous
appointments. If you still have questions, please let me know.
Yours for great science,
Dr. Shawn
Build Your Own Cloud Chamber
Help understanding theory of cloud chamber
Hello,
My name is Monica and I am 6th grade student. My science fair is on Feb.
19, 2009. I purchased the cloud chamber project from Dr. Shawn's science
projects. I need some help understanding this project on a 6th grade
level. I have pulled several things from the web but for some reason, and
maybe it's me making it harder to understand than it is, I just can't
seem to get started on my project report. Doing the actual project, I
think will be no problem - explaining the theory and having a good solid
understanding of it is what I need help on. If you could please help me I
would be forever greatful.
Thanks so very much,
Monica
Re: help understanding theory of cloud chamber
Monica,
This is what I think you need to know at the most basic level. All matter is
made up of atoms which contain protons and neutrons in the nucleus and
electrons orbiting on the outside. Protons are positively charged, neutrons are
neutral, and electrons are negatively charged. Under normal circumstances,
atoms are neutral because they have an equal number of protons and electrons.
However, there is something called ionizing radiation that is all around us. It
is simply any particle or wave that is energetic enough to strip electrons from
atoms making them no longer neutral. Some examples of ionizing radiation are
muons, beta particles, gamma rays, or X rays. I do not think it's important
that you know what all these are at your level. What's important is that you
know that they all are capable of stripping electrons from atoms making them no
longer neutral but charged. When they are no longer neutral they are called
ions. Also you should know that ionizing radiation can come from many different
sources, from outer space, from the ground, or from radioactive sources like
Uranium and is constantly around us. Only we can't see it.
The purpose of your cloud chamber is to make this ionizing radiation visible.
In your cloud chamber what you do is create a very dense cloud of alcohol. The
whole chamber is filled with alcohol but only where it is really dense can you
see it because it has condensed into droplets large enough for us to see. It's
the same with water vapor in the sky. It's all over the place but only where it
is really dense does it form droplets that we can see.
Now, when some ionizing radiation zips through your cloud chamber, as it will
because it's always around us, it will strip away the electrons from some of
the atoms inside the chamber creating a trail of ions where the radiation
zipped through. This line of ions then interacts with the alcohol inside your
cloud chamber basically attracting a whole bunch of alcohol atoms towards the
ions. When this happens, the alcohol atoms become dense enough to form droplets
and be seen by us.
So, when you look inside your chamber in the area just below the alcohol cloud
where the alcohol is not yet dense enough to be visible, you should be able to
see little ghostly cloud tracks or squiggly trails where the ionizing radiation
has zipped through and caused the alcohol to become dense enough to form
droplet trails.
I hope this is helpful to you. Let me know if you have any further questions.
Sincerely,
Dr Michelle
distinguishing different particles
Hello,
We purchased the download on the cloud chamber (order 137111896) for our son's
science fair project and are slightly confused. We are not scientists, but my
husband and I couldn't tell by reading the information how to distinguish the
presence of radon from the radiation particles mentioned in the article. Are we
missing something, or did we misunderstand the scope of information we
received?
Thanks for your help. This is our son's first science fair and we want him to
enjoy the experience.
Ann
Re: distinguishing different particles
Hi Ann,
Radon is an alpha emitter and alphas are heavy, consisting of two protons and
two neutrons. Therefore they'll react strongly inside the chamber and produce
short thick tracks. Most other radioactive sources like muons produce beta
particles instead which are high speed electrons or positrons and will go all
the way through the chamber in thin slender tracks. Hope this helps.
Sincerely,
Dr. Michelle
Viewing an Ant's Brain
How do I take pictures of the insect parts
Dr. Shawn
My son wants to do the ant brain science fair project. Please let me know how I
take pictures of the insects parts and how strong a microscope he needs. How do
you take pictures of what you see in the microscope?
Sue
Jordan's Mom
5th grade student 10 years old
Re: How do I take pictures of the insect parts
Dear Sue,
The secret is simple. Just put the camera against the lens and snap away. If
you take pictures using a digital camera, do so on the highest resolution. Read
the images into your computer and blow them up to a reasonable size.
If the eye piece is too small to be able to get much of an image this way, then
try the following. Remove the eye piece. This will have two lenses in it--the
one you look through (the eye lens) and the one at the bottom. Unscrew the eye
lens and set it aside. Next, tape a small piece of masking tape to the side of
the eye piece. Now, turn the eye piece upside down back into the microscope.
The tape will thicken the side and allow you to snug the eye piece back into
place. The lens that was on the bottom of the eye piece is now on the top. That
lens is much larger than the eye piece and is a whole lot easier to see
through. If you hold the camera above the eye piece you should be able to focus
through the lens and get great pictures of what's on the slide.
As to power, any microscope you find will work perfectly well.
I hope this helps you.
Yours for great science,
Dr. Shawn
EKG PROJECT
leads for the data-logger
Dear Dr.
Shawn
I had a couple of questions about the download for the ecg. I was wondering
where to connect the leads for the data-logger for one. I would think that the
red lead would be connected to the output of the ecg, but where should the
black lead be connected to? Should it just be connected to the ground or where?
I was also wondering what should the potentiometer be adjusted to?
Thank you for your time.
James Swigert
Re: leads for the data-logger
Dear James,
The red lead goes to the output of the ECG. As you suspect, the black lead goes
to the ground connection. The variable resistor is a zero-adjust. Adjusting the
resistor will move the output voltage up or down. So watch the trace as you
adjust the resistor and set it so that the trace is centered around zero
voltage.
We definitely should explain that in the instructions. Thanks for letting me
know that this needs improvement.
Take care,
Dr. Michelle
-9 volt lead
Dear Dr.
Michelle
My son is doing the homemade ecg for his science fair and I had a questions
about the schematic. On the diagram it shows that you apply a +9v after the the
low pass filter. I was wondering where the -9v lead comes into play to finish
that part of the circuit?
Thank you for your time.
James
Re: -9 volt lead
It doesn't.
The -9V is only used to power the chip.
Dr. Michelle