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Suggestions for materials for a physics home
lab
Compared to setting
up a chemistry home lab, setting up a nice home lab for physics experiments
is much more difficult. The science of physics is very broad and it strongly
depends on what you want, what you should purchase.
Physics, more than any other science, is strongly biased
to having equipment. Equipment can be as simple as a few magnets to something as
complex as a setup for subatomic particle experiments. The available financial
resources severely limit what can be setup at home.
A few things, however, are suitable for home experimenting
and can already prove to be very interesting and equipment can be setup at
reasonable cost.
- electronics, both analog and digital
- high voltage electrical experimenting
- magnetism
- mechanics
A few things, which really are worth the money are the
following:
- A simple multimeter, capable of measuring voltages
and currents. It is nice if it also can measure resistance. Simple, yet
quite accurate multimeters are available for $20, or even less. I purchased
a Velleman DVM850bl for just €15 and it works very well:
- A power supply, capable of producing an adjustable
voltage from 5 to 30 volts. A symmetric power supply with positive and
negative power rails is a very important piece of equipment for the
electronics hobbyist. For more general physics hobbyists, a simple power
supply with a single power rail is sufficient. At low budget, one even can
buy a simple fixed voltage power supply, such as the PS1310, which provides
a maximum of 10 A at 13.8 V. One should not bother of building such a device
himself, it simply is not worth the effort and cost. I purchased a simple
PS1310 for €45, and I modified it slightly to reduce ripple voltage (out of
the box that is 200 mV at 10 A, by adding a big capacitor inside, I reduced
this to less than 100 mV).
- When you do electronics, then it is best to have good
stock of some common components. Buying them in bulk from an eBay
seller makes a single fairly large investment, but the components are MUCH
cheaper, than when purchased at a local supplier. I added
standard carbon film resistors from the E12 series to my lab, starting at 10
Ω, and ending at 1 MΩ. I also added diodes of the type 1N4007 (general
purpose, 1 A maximum current and 1000 V reverse breakdown voltage), I added
a handful of capacitors, ranging from a few hundreds of pF to approximately
1 μF. Finally, I added a bunch of simple general purpose transistors, type
BC547C and BC557C, and a few general purpose JFET input opamps, TL081. This
was a one-time investment of almost $100, but when these components had to
be purchased locally, I would have spent more than 3 times as much. Look at
eBay for sellers of electronic components. There are quite a few and they
have good prices, provided you buy in larger quantities.
- Any physics lab should have plenty of test leads,
preferably with banana connectors, and also some connectors with crocodile
clamps.
- If you do high voltage experiments, then you need
some high voltage source. I have built two power supplies, a
little one for medium voltages, up to
approximately 300 V, and a large one for voltages
up to 10000 V. I also have a HV-unit from an old oscilloscope, capable
of delivering a voltage of over 15000 V, but only at very low current (a few
hundreds of μA). Such HV-sources can sometimes be purchased as surplus part
on eBay for a low price.
- Very interesting experiments can be done with gas
discharge tubes of all kinds. It definitely is worth the money to invest in
a few of them. Cheapest are the simple NE-2 bulbs, which can be purchased at
eBay for less than $10 for 50 of them, interesting tubes also are in
fluorescent lamp starters, which can be purchased at hardware stores. These
can be either neon (orange discharge) or argon (purple discharge) tubes.
Finally, xenon flash tubes also are quite interesting. These can be
purchased at electronics parts stores for approximately $5 per item.
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If you perform
experiments with gas discharges, then you definitely need a power
supply, such as the small one for a few 100's of volts, as described
above. Also, a trigger transformer for a xenon tube can come in handy,
if you don't want to handle really high voltages of several kV. |
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Experiments with gas
discharge tubes can be of all kinds. Oscillators can be built with them,
they are interesting in light and radiation sensor experiments, and they
are interesting in all kinds of sparking and plasma experiments. |
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Finally, a very
interesting type of discharge tubes are so-called spectrum tubes. These
are filled with a gas of known purity and are designed, such that they
show the spectrum of the light of the discharge very well. These tubes
are available from specialized suppliers (search for gas
spectrum tube). Here follow some pictures of these tubes. These
tubes, however, are quite expensive, their price ranges from $20 to $40
per tube. Browse around on the Internet carefully, prices for similar
tubes vary widely from supplier to supplier. If you want to experiment
with gas spectrum tubes, then you need a current-limited power supply,
capable of producing a few kV at least. |
- Neodymium iron boron magnets also are interesting to
add to the physics lab. These are very powerful magnets and can be purchased
in many sizes, ranging from a few mm to several cm. It is best to purchase a
pack of different size magnets in one go. Do not buy the really large ones
of more than a few cm. These are very strong and pose a serious risk of
punching fingers or injuring in another way. The little sticks of a few mm
diameter and a length of 1 cm or slightly more are the most interesting.
These magnets are interesting in conjunction with gas discharge experiments,
in conjunction with low voltage current experiments, and also on their own.
These magnets are available on eBay from many different sources. With some
patience, you can sometimes find really good auctions. I purchased the
following set for only €10.50 (appr. $13), but you have to have some luck
for this and to check out regularly. When these magnets are purchased
separately, then you pay at least 5 times as much.
- Also a must in a physics lab are some bigger
capacitors. These can be used to show many interesting effects, especially
in combination with magnets, or with gas discharges. I was given a few low
voltage electrolytic capacitors of 10000 μF / 30 V. I purchased a lot of 50
capacitors of 220 μF / 400 V from eBay, and I purchased several high voltage
capacitors (4700 pF / 6300 V, 2200 pF / 15000 V) and a few huge capacitors
(40 μF / 5000 V). The really high voltage capacitors (more than a few
hundreds of volts)
only are needed for some specialized high voltage experiments, such as
building Marx generators, Cockcroft Walton voltage multipliers, and
discharge experiments. But at least, having around a few larger low voltage to
medium voltage capacitors adds a lot to the lab, even if you do not
do real electronics. The pictures below show a high voltage pulse discharge
capacitor (40 μF/5000 V). These pictures nicely show how large these
capacitors are. They are Russian army make and are VERY robust. They also
easily withstand 7500 V.
- If you are doing high voltage experiments, then you
also need some high voltage resistors. These are needed for measuring, but
also can be useful for building high voltage circuits. Such high voltage
resistors must have very high resistance, and they also must withstand many
kV. These resistors are extremely expensive and hard to get your hands on.
However, from ordinary resistors, one can build such high voltage resistors.
I made two 500 MΩ resistors from 22 MΩ resistors and 10 MΩ resistors, by
soldering long strings of ordinary resistors. The pictures below show how
these are made. After such strings of resistors were soldered, they were
covered by a thick layer of transparent lacquer and mounted in nice plastic
boxes with strong terminals. The lacquer is important to reduce corona
losses in the resistor. Each of these resistors can withstand appr. 20 kV.
These resistors also are used as a 1 : 1000 probe with the multimeter,
mentioned above. The total resistance of both resistors is 1 GΩ, and the
input resistance of the multimeter is 1 MΩ. By using these in series with
the multimeter, these resistors allow the measurements of voltages to a few
tens of kV with high accuracy.
- General material like strips of metal (zinc, copper,
aluminium), transparent glass beakers, incandescent tungsten bulbs for
several voltages, LED's, small mirrors, lenses, etc. always come in handy
with many experiments. Don't spend too much cash on these, but look around
carefully. Many people have stuff lying around, which can be really useful
in your science lab, while they intend to throw it away (e.g. waste metal
strips from a building project, parts from a broken mirror, parts from an
old camera or flash unit).
With the materials, mentioned above, one can do quite a
few interesting and fun experiments. Sometimes, even plain household items can
do quite interesting experiments. On this site, many interesting experiments
will be described, some of them using more specialized materials, others can be
done with very simple equipment and show unexpected possibilities of well-known
and common materials. |