Physics 011

Answers of PQ#16

1.	Electrons carry a The correct answer: negative charge. Review Section 16-2 in Giancoli.
2.	The units of Coulomb's constants are The correct answer: Nm^2/C^2 Review Section 16-5 in Giancoli.
3.	The units of permittivity are The correct answer: C^2/Nm^2 It is the reciprocal of Coulomb's constant. Review Section 16-5 in Giancoli.
4.	The unit of a charge is the Your answer: C(oulomb)
5.	Which of the following are the units of electric field? The correct answer: N/C Review Section 16-7 in Giancoli.
6.	Two charges Q1 and Q2 are separated by a distance D. If the distance is doubled, the force is The correct answer: decreased by a factor of 4. Close but it will decrease. Review Section 16-5 in Giancoli.
7.	Two charges Q1 and Q2 are separated by a distance D. If Q1 is doubled, the force is Your answer: increased by a factor of 2.
8.	Two charges Q1 and Q2 are separated by a distance D. If Q1 and Q2 are doubled, the force is The correct answer: increased by a factor of 4. This would be true if only one was doubled. Review Section 16-5 in Giancoli.
9.	Two charges Q1 and Q2 are separated by a distance D. If both Q1 and D are doubled, the force is The correct answer: decreased by a factor of 2. Review Section 16-5 in Giancoli.
10.	Two charges Q1 and Q2 are separated by a distance D. If Q1, Q2 and D are all doubled, the force is The correct answer: remains the same. Review Section 16-5 in Giancoli.
11.	In the above figure, if Q1 is negative and has magnitude less than Q2 which is positive, where could a positive charge be placed and possibly have a zero net force on it? Your answer: A
12.	In the above figure, if Q1 and Q2 are positive, where could a negative charge be placed and have a vertically upward net force on it? The correct answer: D Review Section 16-4 in Giancoli.
13.	In the above figure, if Q1 and Q2 are positive, where would the electric field be vertically upward ? The correct answer: B Review Example 16-8 in Giancoli.
14.	In the above figure, if Q1 and Q2 are positive and the same size, where would the electric field be zero ? The correct answer: E Review Example 16-7 in Giancoli.
15.	In the above figure, if Q1 is negative and Q2 is positive and are both the same magnitude, where would the electric field be zero ? The correct answer: Nowhere shown. Review Example 16-8 in Giancoli.
16.	In the above figure, if Q1 is negative and Q2 is positive and the distance from Q2 to point C is 1/4 the distance between the charges, how many times greater than Q2 in magnitude must Q1 be for the Electric field to be zero at C? The correct answer: 25 Q1 is 5 times further away. Review Section 16-7 in Giancoli.
17.	In the above figure if the vertical distance from point E to B is the same as the horizontal distance from E to either charge and the electric field at B from either charge has magnitude 1.0x10^6, what is the magnitude of the net electric field? The correct answer: 1.4x10^6 They are not colinear. Review Example 16-8b in Giancoli.
18.	In the above figure the vertical distance from point E to B is the same as the horizontal distance from E to either charge and the electric field at B from either charge has magnitude 1.0x10^6. If Q1 is negative and Q2 is positive what is the direction of the net electric field at B? The correct answer: Horizontal and to the left. Review Example 16-8 in Giancoli.
19.	In the above figure the vertical distance from point E to B is the same as the horizontal distance from E to either charge and the electric field at B from either charge has magnitude 1.0x10^6. If both Q1 and Q2 are positive what is the direction of the net electric field at B? Your answer: Vertical and up.
20.	The figure above shows a metal shell surrounding a positive charge. What is the charge on the metal surface at b? Your answer: negative
21.	The figure above shows a metal shell surrounding a positive charge. Which of the following statements is true? The correct answer: The electric field at c is less than that at a and e. Review Section 16-9 in Giancoli.
22.	In question 20 what would be the charge on the exterior surface (d)? Your answer: positive
23.	Four people tell you they have a negative charge of a certain value. Which one is not telling the truth? The correct answer: Mine is 1.90x10^-18 Coulomb. Review Section 16-5 in Giancoli.
24.	What must be the charge on each of two 100 kg spherical masses in order for the electrical force to equal the gravitational force? The correct answer: 8.6 nanoC Review Section 16-5 in Giancoli.
25.	How many electrons would it take to make up a charge of minus one millionth of a Coulomb? Your answer: 6.25x10^12