The first thing you should be concerned about in the lab is the safety of yourself and your fellow students. There are a number of potentially serious hazards in this lab, but if you are aware of the dangers and use sensible precautions, you will be quite safe.
Electrical hazardsElectrocution is by far the most serious hazard. You will
be working continually with electrical equipment, which
sometimes uses high voltages. You should always be aware
when you are working near exposed wires, and whenever you
are changing high voltage electrical connections always
double check that the power is turned off, and any
capacitors, either inside the power supply or outside, are
discharged. One of the primary dangers of working with
high voltages is that you do not have to actually touch a
wire to be shocked‑ the current can arc to your body even
if you are a few mm away. A good standard practice
when working with exposed high voltage is to always keep
one hand in your pocket to avoid the possibility
of a current entering your body through one hand and
leaving through the other, because it is closest to
ground. The reason this is particularly bad is that the
current will pass through your heart and start it
fibrillating. Most accidental electrocutions are due to
fibrillation. For this reason the most lethal voltage
levels are around 400-500 V, since this is most likely to
lead to currents which cause fibrillation. Higher voltages
(for example, 2000 V), while still dangerous, tend to
cause the heart muscle to simply spasm, but beating will
usually resume if the voltage is removed quickly. High
voltage, high current sparks frequently cause very deep
burns which take a long time to heal. The 120 V line power
is relatively safe, but still can provide painful shocks
and can be quite dangerous if your body is a relatively
low resistance path, for example if your hands are wet
when you touch the wire. Voltages below 50 V usually
involve little danger.
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