physics 203

A plastic rod is charged up by rubbing a wool cloth and brought to an initial neutral metallic sphere that is insulated by the ground. It is allowed to touch the sphere for a few seconds, and then is seperated from the sphere by a small distance. After the rod is seperated, the rod A) repelled by the sphere B) is attracted to the sphere C) feels no force due to the sphere

A) repelled by the sphere

A small charged plastic ball is vertically above another charged small ball in a frictionless test tube. The balls are in equilibrium a distance d apart. If the charge on each ball is doubled, the equilibrium distance between the balls in the test tube would become A) root 2d B) 2d c) 4d D) 8d E) d/4

B) 2d

Consider a uniform horizontal electric field of No N/C directed towards the east. If the electric potential at a given point in the field is 80 V, what is the potential at a point 1.0 m directly east of the point? A) 15 V B) 30 V C) 90 V D) 130 V

B) 30 V

A proton and an electron are released from rest, with only the electrostatic force acting. Which of the following statements must be true about them as they move toward each other? A) Their electric potential energy keeps increasing B) Their kinetic energy keeps increasing C) their electric potential energy keeps decreasing D) their kinetic energy keeps decreasing E) their acceleration keeps decreasing

B) Their kinetic energy keeps increasing C) their electric potential energy keeps decreasing

an electron and a proton are released simultaneously from rest and start moving toward each other due to their electrostatic attraction, with no other forces present. Which of the following statements are true just before they are about to collide? (more than one) A) they are closer to the initial position of the electron that to the initial position of the proton B) They are closer to the initial position of the proton that the initial position of the electron C) they are at the midpoint of their initial separation D) The both have the same speed

B) They are closer to the initial position of the proton that the initial position of the electron

Two uncharged metal sphere #1 and #2 are mounted on insulating support rods. A third metal sphere, carrying a positive charge is then placed near #2. Now a copper wire is momentairly connected between #1 and #2 and then removed. Finally, sphere #3 is removed. In this final state A) sphere #1 and #2 are still uncharged B) sphere #1 carries positive charge and #2 carries negative charge C) Sphere #1 carries negative charge and #2 carries positive charge D) spheres #1 and #2 both carry positive charges E) spheres #1 and #2 both carry negative charges

B) sphere #1 carries positive charge and #2 carries negative charge

What charge accumulates on the plates of a 2.0 microF air-filled capacitor when it is charged until the potential difference across its plates is 100 V A) 50 microC B) 100 microC c) 150 microC D) 200 microC

D) 200 microC

Which of the following changes will increase the capacitance of a parallel plate capacitor? A) increase the charge on the plates B) decrease the potential between the plates C) increase the potential between the plates D) Introduce a dielectric material between the plates E) decrease the separation between the plates

D) Introduce a dielectric material between the plates E) decrease the separation between the plates

As a proton moves in the direction the electric field lines A) it is moving from low potential to high potential and gaining electric potential energy B) it is moving from low potential to high potential and losing electric potential energy C) it is moving from high potential to low potential and gaining electric potential energy D) it is moving from high potential to low potential and losing electric potential energy E) both its electric potential and electric potential energy remain constant

D) it is moving from high potential to low potential and losing electric potential energy

Which statements must be true about the surface of the charged conductor in which no charge is moving? A) The electric field is zero at the surface B) the electric potential of the surface is zero C) the electric field is constant at the surface D) the electric potential is constant over the surface E) the electric field is perpendicular to the surface

D) the electric potential is constant over the surface E) the electric field is perpendicular to the surface

If two objects are electrically attracted to each other, A) both objects must be negatively charged B) Both objects must be positively charged C) One object must be negatively charged and the other object must be positively charged D) the objects could be electrically neutral E) none of the above

D) the objects could be electrically neutral

As a proton moves in a direction perpendicular to the electric field lines A) it is moving from low potential to high potential and gaining electric potential energy B) it is moving from low potential to high potential and losing electric potential energy C) it is moving from high potential to low potential and gaining electric potential energy d) it is moving from high potential to low potential and losing electric potential energy E) both its electric potential and electric potential energy remain constant

E) both its electric potential and electric potential energy remain constant

The electron-volt is a unit of A) charge B) electric potential C) electric field D) electric force E) energy

E) energy

Two equal and opposite charges are a small distance apart, forming an electric dipole. a positive charge +q is placed above these charges, as shown in the figure, equidistant from both of them. which diagram below best gives the direction of the net force the dipole exerts on the charge +q? A) up B) down C) right d) left

c) right