Electrostatic Electricity, Electric Charge (CH 15 Homework No. 1 (Electrostatics) Due date: October 4 or 5 October 2016 Name: _____________________ If you rub a glass rod with a silk cloth: a) what charge polarity will the glass rod acquire?); (b) What method of charge transfer is being used? __________________________________________________ If you charge a glass rod and balloon each with a silk cloth, will the rod and balloon attract or repel each other? ______________________________________________________________________________ No. 23 In calculating planetary orbits around the sun, why can astronomers safely ignore the electric force? ______________________________________________________________________________ No. 26 Coulomb’s Law is also called an inverse square law. What does it tell you about the relationship between force and distance? ____________________________________________________________ An electron and a proton are separated by 2.0 nm. Using the Coulomb’s Law we can calculate the magnitude of the force on the electron, F = k(q1 x q2)/r2.= 5.8x 10-11 N; What is the net force on the system? _____________________________________________________________________________ The electric field due to negative charge (a) varies as 1/r; (b) points toward the charge, (c ) points away from the charge or (d) has a finite charge. __________________________________________________ Could the electric field due to two charges ever be zero at some location nearby? If yes,describe and sketch the situation. ____________________________________________________________________

Electrostatic Electricity, Electric Charge (CH 15) (with answers) Homework No. 1 (Electrostatics) Due date: October 4 or 5 October 2016 Name: _____________________ If you rub a glass rod with a silk cloth: a) what charge polarity will the glass rod acquire? A: Glass is positive); b) What method of charge transfer is being used? A: By contact If you charge a glass rod and balloon each with a silk cloth, will the rod and balloon attract or repel each other? A: attract No. 23 In calculating planetary orbits around the sun, why can astronomers safely ignore the electric force? A: 23c Objects are electrically neutral. No. 26 Coulomb’s Law is also called an inverse square law. What does it tell you about the relationship between force and distance? A.: Force depends on inverse square of the distance between the charges. An electron and a proton are separated by 2.0 nm. Using the Coulomb’s Law we can calculate the magnitude of the force on the electron, F = k(q1 x q2)/r2.= 5.8x 10-11 N; What is the net force on the system? A: zero because the two forces add up to zero. 6) The electric field due to negative charge (a) varies as 1/r; (b) points toward the charge, (c ) points away from the charge or (d) has a finite charge. A: b Could the electric field due to two charges ever be zero at some location nearby? If yes, describe and sketch the situation. A: 49 Yes! When the electric fields are equal in magnitude and opposite in direction at a location. q2 F2 F1