Electrostatic deflection

Chapter Electrostatic deflection

Teach Yourself Electricity and Electronics Third Edition Book
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Summary of Contents

Teach Yourself Electricity and Electronics Third Edition Book

  • Electrostatic deflectionElectric fields produce forces, just asdo magnetic fields. You have probably noticed thiswhen your hair feels like it’s standing on end in very dry or cold weather. You’ve proba-bly heard that people’s hair really does stand straight out just before a lightning bolt hitsnearby; this is no myth. Maybe you performed experiments in science classes to ob-serve this effect.The most common device for demonstrating electrostatic forces is the electro-scope. It consists of two foil leaves, attached to a conducting rod, and placed in a sealedcontainer so that air currents will not move the foil leaves (Fig. 3-3). When a chargedobject is brought near, or touched to, the contact at the top of the rod, the leaves standapart from each other. This is because the two leaves become charged with like electricpoles—either an excess or a deficiency of electrons—and like poles always repel.46 Measuring devices3-2Circuit for demonstratinghow a galvanometerindicates relative current.3-3A simple electroscope.The extent to which the leaves stand apart depends on the amount of electric charge.It is somewhat difficult to actually measure this deflection and correlate it with chargequantity; electroscopes do not make very good meters. But variations on this theme can