Question
A small amount of charge is placed on both an isolated conducting sphere and an isolated insulating sphere. For both spheres, the charge is added at a small area at the top of the sphere. After a few seconds, where on each of the spheres is the charge that was added?
Conducting Insulating
(A) At the top At the top
(B) At the top Spread over the surface
(C) Spread over the surface At the top
(D) Spread over the surface Spread over the surface
▶️Answer/Explanation
Ans:C
Question
An initially uncharged electroscope consists of two thin, 50 cm long conducting wires attached to a cap, with a 25 g conducting sphere attached to the other end of each wire. When a charged rod is brought close to but not touching the cap, as shown above, the spheres separate a distance of 30 cm. What can be determined about the induced charge on each sphere from this information?
(A) The magnitude but not the sign
(B) The sign but not the magnitude
(C) Both the magnitude and the sign
(D) Nothing can be determined about the induced charges.
▶️Answer/Explanation
Ans:A
Question
Two electrically neutral conducting rods are near a negatively charged sphere, as shown in the figure above. Rod 1 is touched to rod 2 for several seconds, and then the rods are separated. The rods are then both removed from the vicinity of the charged sphere. Which of the following best describes the resulting net charge on each rod?
(A) Rod 1 is positively charged, and rod 2 is negatively charged.
(B) Rod 2 is positively charged, and rod 1 is negatively charged.
(C) Rods 1 and 2 are both negatively charged.
(D) Rods 1 and 2 are both uncharged.
▶️Answer/Explanation
Ans:
A
Question
Which of the following charges is NOT possible?
(A) \(4.8\times10^{-19}C\)
(B) \(4.8\times10^{-18}C\)
(C) \(4.8\times10^{-20}C\)
(D) \(-4.8\times10^{-19}C\)
▶️Answer/Explanation
Ans:(C)
Charge is quantized (comes in integer multiples only) in units of \(\pm1.6\times10^{-19}C\).
Question
One joule of work is needed to move one coulomb of charge from one point to another with no change in velocity. Which of the following is true between the two points?
(A) The current is one ampere.
(B) The potential difference is one volt.
(C) The electric field strength is one newton per coulomb.
(D) The electric field strength is one joule per electron.
▶️Answer/Explanation
Ans:B
Solution: W = qV