Physics Safety Issues

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.

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