A current is established in a gas discharge tube when a sufficiently high potential difference is applied across the two electrodes in the tube. The gas ionizes; electrons move toward the positive terminal and singly charged positive ions toward the negative terminal. (a) What is the current in a hydrogen discharge tube in which 3.1 X 10 18 electrons and 1.1 X 10 18 protons move past a cross-sectional area of the tube each second? (b) Is the direction of the current density 7 toward or away from the negative terminal?
• KeyPoints o UnitofforceandmagnitudeismeasuredinNewtons o Direction=+or- o ObjectofInterest:theobjectbeinganalyzed o Makesuretoaskyourself,“Isitfalling” o NetForce:thesumofforces o Equilibrium:netforce=0 o System:objectofinterestandobjectexertingforcesonit o Contactforce:theforcewheretwoobjectsmeet o Forcediagrams:representforcesexertedonobjectofinterest • ForceDiagrams 1. Useadotforobjectofinterest. F(HAND) 2. Labelobjectofinterest.(PoolBall) 3. Listforcesthatotherobjectsexert