Whether
your laboratory looks like a high tech facility or the remnants of a
science fiction horror show, you face the challenge of grabbing the
attention of your students and guiding them through the study of physics
- safely. The diversity and
age of your equipment present unique situations by which you must
determine whether your equipment, facility, and students can safely
complete each laboratory experiment or demonstration.
Safety is a learned behavior that you must incorporate into your
instructional plans. The
physics teacher should be cognizant of potential hazards by conducting
all experiments and demonstrations prior to classroom implementation.
Dangerous situations may occur quickly and teachers need to
possess knowledge and preparedness in order to practice safety with
confidence and control.
As mentioned in the general guidelines for all science
disciplines, you should assess your laboratory and classroom environment
for safety and submit the appropriate documentation to your
administrator stating your concerns.
Some laboratory manuals currently used by the Akron Public
Schools recommend the use of their safety contracts.
(See Appendix) There are several safety aids commercially available through
suppliers such as Flinn Scientific, Inc.
These aids include posters, safety contracts, safety tests,
safety citations, texts, and handbooks on secondary science safety and a
variety of safety equipment. In
addition to observing policy of the Akron Public Schools, you need to
review the procedures of your individual school.
These considerations are not intended to be all inclusive but to
serve as a catalyst to encourage the review of current safety practices
and the reinforcement of those areas deemed necessary by the teacher.
The specific experiments and demonstrations presented in the
physics curricula vary depending upon the equipment available and the
expertise and confidence of the teacher.
Included
in this Section:
·
Electricity
·
Energy
·
Heat
·
Pressure
·
Light
·
Lasers
·
Sound
·
Radiation
·
Radioactivity
Safety
Considerations for Specific Physics Topics
Electricity
. Locate
the master electrical cut-off switch.
.
Use low voltage DC for studying simple circuits.
.
The teacher should check all student circuits before the power is
connected.
.
Never touch electrical circuit components with the power on.
Only insulated tools should be used to make checks.
.
The last act in assembling a wired electrical circuit is to
insert the plug. The first
act in disassembling a wired electrical circuit is to remove the plug.
.
When using an electrical current, you should use only one hand at
a time to avoid bringing both hands in contact with live sections of the
circuit.
.
Electrical batteries should be checked for leakage and not be
left in electrical appliances for extended periods of time.
.
If electrical current is used near a metal object, the object
should be permanently insulated to prevent contact.
Care should be taken to assure that live wires do not contact
grounded metal objects.
.
Keep away from the fine spray that develops when charging a
storage battery.
.
Carefully handle a storage battery.
In spite of its low voltage, a high current can be drawn from it
on a short circuit.
.
Switches should be labeled for "on" and "off"
positions.
.
Proper grounding of equipment should be checked by the teacher
before using.
.
Any equipment with frayed cords or any other visible defects
should not be used.
.
Installation and repair to electrical equipment should not be
done by an amateur. Check
with your administrator for the appropriate procedures for equipment
repair.
. Plugs
should always be plugged in and pulled out using the plug, not the wire.
.
Use properly grounded (3 prong - one constant ground) service
outlets.
.
Care should be taken not to spill liquids near electrical
outlets.
.
All potentiometers should be checked by the teacher before use in
circuits by students.
. If fire does occur with a "live" electrical apparatus, pull the
plug then use an
appropriate fire extinguisher (Class C), dry chemical - carbon
dioxide.
Motion
and Forces
. Teachers
should make sure that devices that are to be stationary should be
secured by a C-clamp.
.
Spring-loaded carts and heavy masses should be used only as
directed.
.
Centripetal force labs should be conducted only with protective
goggles. If glass rods are
used, they should be fire polished and wrapped in tape.
Additional space may be needed to assure the spinning mass does
not hit anything. Instructions
should be given to caution students never to walk in the path of the
spinning masses. Finally,
the teacher should check to assure that the mass being used by each
group is securely fastened.
.
The building and testing of model bridges warrants some
precautionary measures. The
use of Exacto knives should be supervised carefully.
Protective goggles should be worn by everyone when breaking
bridges. Caution students
to the potential hazards of the container of masses.
.
A planetary motion hazard is the viewing of solar eclipses.
Never view solar eclipses directly; always use an indirect
method. (Refer to Earth
Science for specific procedures.)
.
When using model rockets, the safety code of the National
Association of Rocketry (NAR) should be followed.
Only factory prepared solid engine propellant should be used and
only as recommended by manufacturers.
Direct supervision is needed by the teacher.
(Refer to Earth Science for specific procedures.)
.
When using any apparatus that rotates, be sure the safety nut is
secured.
Energy
. Ring
stands should be secured with a C-clamp.
.
Springs should not exceed their elastic limits.
.
When viewing the pointer on a fixed scale, goggles should be
worn.
.
Sufficient space must be allowed during activities involving
collisions.
Heat
. Locate
master gas valve cut-off and leave master control "off" when
not in use.
.
Closed containers should never be heated.
.
Use proper technique to insert a thermometer into a rubber
stopper to prevent lacerations. (Refer
to Biology or Chemistry for specific procedures.)
.
Goggles and insulated gloves should be worn when using cryogenic
fluids.
.
Bunsen burners should be periodically checked.
.
Fire retardant pads and gloves should be used when handling hot
materials.
.
Only Pyrex glassware should be used when heating liquids.
.
Never leave gas jets open.
.
Refer to Chemistry section for the proper procedure for cleaning
up broken mercury thermometers.
.
A fire blanket and an appropriate fire extinguisher should be
available in the vicinity.
Pressure
. When
using a pressure cooker, do not allow the pressure to exceed 20 pounds
per square inch; allow the cooker to cool to room temperature before
opening it.
.
The use of mercury manometers can be hazardous due to the
poisonous vapors of mercury. Place
a few drops of oil in each tube to cover the mercury and prevent the
vapors from escaping. When
not in use, the apparatus should be tightly covered and stored securely
in a well ventilated room. The
teacher is directed to the Chemistry section for the correct procedures
to clean up mercury spills.
Light
. Mirrors
that are sharp should be taped. Jagged-edged
mirrors should be discarded.
.
The use of lenses and prisms in direct sunlight should be
supervised.
.
Caution should be exercised in the use of ultraviolet light
sources, such as mercury-quartz lamps or carbon arc lamps that can cause
severe sunburn or damage to the retina.
Proper instructions, labels, and protective gear should be
provided.
.
Wave motion, when studied with light, generally includes the use
of large coil springs or rubber hoses.
Care should be given not to exceed the elastic limit of the coils
or to release the hose unexpectedly.
.
Ripple tanks should be set up to assure the stability of the high
intensity light, the motor, and the electrical source.
.
When simulating Young's experiment, caution should be given to
handling the delicate slides and the single edge razor blades.
.
Spectroscope high voltage supplies should be checked prior to
classroom use. Students
should be cautioned never to touch the ends of the spectrum tube while
the voltage supply is connected.
.
Some students may have physiological or psychological reactions
to the effects of a strobe light. (e.g., epilepsy)
Lasers
. Never
permit eye exposure to either direct or reflected laser light.
.
Target must be made of non-reflecting material.
.
Beams should not be set at eye level.
.
Students should not move about the room during the activity.
.
The teacher should operate the laser at the lowest possible power
and maintain the room's illumination bright enough so that the pupils of
the eye remain small.
.
Prisms should be set up before class to avoid unexpected
reflections.
.
Appropriate beam stops should be used to terminate the laser beam
where needed.
.
An adequate laser for high school use is the .5 milliwatt
Helium-Neon laser.
.
It is recommended that students wear approved laser goggles.
Sound
. When
using the high speed siren disk, the teacher should securely fasten the
safety nut. The apparatus
should be used only at moderate speeds.
.
When studying resonance, the vibrating tuning forks must not
touch the top of the glass tube for there is danger in shattering the
tube. Placing tape on the
rim of the tube will reduce chipping.
.
In the production of sound, the teacher should be aware that
sound levels of 110 decibels or higher can cause hearing damage.
Radiation
. If
you elect to use any radiation emitting devises, be fully aware of their
hazards and the cumulative effects.
Proper shielding must be used when using an apparatus that
generates X-rays, such as the heat effect tube, magnetic or deflection
tube, and the shadow or fluorescence tube. These tubes should only be used for demonstrations presented
by the teacher.
.
If vacuum tubes become brittle the low internal pressure
increases the potential for implosions.
Check tubes periodically.
·
Cathode ray tubes should
be incased in a frame and only the teacher should move them from the
storage room to the classroom and back.
·
Teachers should use the
lowest voltage possible and have the students view from a minimum
distance of eight feet.
Radioactivity
·
The teacher must be
properly trained in the use of radioactive materials.
·
The teacher should be
knowledgeable that there is a limit to the quantity of radioactive
materials that an individual may possess for instructional use without
having to obtain a license issued by the Nuclear Regulatory Commission
(NRC).
·
All radioactive materials
must always be handled with gloves or tongs.
·
The students should never
handle the apparatus or materials until given explicit instruction by
the teacher.
·
Students should not be
permitted to work with the radioactive isotopes for an extended period
of time.
·
The exposure to radiation
from a source is reduced to one-fourth as you double your distance from
the source.
·
Proper shielding can
reduce radiation effectively.
·
Care should be given to
the handling of an apparatus used to measure the quantity of
radioactivity. The teacher
should be aware that the “window” area of the tube is considered
delicate.
·
Disposal of any
radioactive materials should comply with the “Rules and Regulation”
of the NRC. The wastes
should never be disposed of via the waste basket.
