potentialandcapacitor(电势和电容).docVIP

Chapter 17 electric potential and capacitor A +0.20C charge is in an electric field. What happens if that charge is replaced by a +0.40C charge?(a) The electric potential doubles, but the electric potential energy stays the same.(b) The electric potential stays the same, but the electric potential energy doubles.(c) Both the electric potential and electric potential energy double.(d) Both the electric potential and electric potential energy stay the same. Two identical positive charges are placed near each other. At the point halfway between the two charges,(a) the electric field is zero and the potential is positive.(b) the electric field is zero and the potential is zero.(c) the electric field is not zero and the potential is positive.(d) the electric field is not zero and the potential is zero.(e) None of these statements is true. 3. Four identical point charges are arranged at the corners of a square [Hint: Draw a figure]. The electric field E and potential V at the center of the square are(a)E=0 ,V=0 (b)E=0 ,V0 (c)E0 ,V0(d) E0 ,V=0 (e) E=V, regardless of the value. 4. Which of the following statements is valid?(a) If the potential at a particular point is zero, the field at that point must be zero.(b) If the field at a particular point is zero, the potential at that point must be zero.(c) If the field throughout a particular region is constant, the potential throughout that region must be zero.(d) If the potential throughout a particular region is constant, the field throughout that region must be zero. If it takes an amount of work W to move two +q point charges from infinity to a distance d apart from each other, then how much work should it take to move three point +q charges from infinity to a distance d apart from each other?(a) 2W. (b) 3W. (c) 4W. (d) 6W. A proton (Q=+e) and an electron (Q=-e)are in a constant electric field created by oppositely charged plates. You release the proton from