1. When charging two objects by rubbing them together: a. Neither may be a condu
ID: 2003593 • Letter: 1
Question
1. When charging two objects by rubbing them together:
a.
Neither may be a conductor.
b.
They must be made of different material.
c.
They will sometimes end up with both being positively charged.
d.
The heat produced by friction is a necessary part of this process.
2. Who was the first to determine the electron’s charge?
a.
Franklin
b.
Coulomb
c.
Millikan
d.
Faraday
3. The combination of two separated point charges of opposite sign but equal magnitude is called an electric:
a.
monopole.
b.
dipole.
c.
quadrapole.
d.
magnapole.
4. An airplane is flying through a thundercloud at a height of 3,000 m. (This is a very dangerous thing to do because of updrafts, turbulence, and the possibility of electric discharge.) If there is a charge concentration of +38 C at height 4,000 m within the cloud and 38 C at height 1,500 m, what is the magnitude of the electric field E at the aircraft? (ke = 8.99 × 109 N·m2/C2)
a.
151,831 N/C
b.
341,620 N/C
c.
109,318 N/C
d.
493,451 N/C
e.
303,662 N/C
5. Two point charges each have a value of 31.7 mC and are separated by a distance of 4 cm. What is the electric field midway between the two charges? (ke = 8.99 × 109 N·m2/C2)
a.
56.5 × 107 N/C
b.
28.2 × 107 N/C
c.
14.1 × 107 N/C
d.
zero
e.
17.8 × 107 N/C
6. Two small objects are suspended from threads. When the objects are moved close together, they attract one another. Which of the following could produce this result?
a.
One object is positively charged and the other is negatively charge.
b.
One object is positively charged and the other is uncharged.
c.
One object is negatively charged and the other is uncharged.
d.
All of the above could result in such attraction.
7. An initially uncharged hollow metallic sphere with radius of 2 cm has a small object with a charge of +10 µC carefully placed at the center of the sphere through a hole in the latter’s surface. With the charge in place, what charge is now present on the outside surface of the sphere?
a.
zero
b.
10 µC
c.
+4,000 µC
d.
+10 µC
e.
4,000 µC
8. The number of electric field lines passing through a unit cross sectional area is indicative of:
a.
field direction.
b.
charge density.
c.
field strength.
d.
charge motion.
9. A charge Q accumulates on the hollow metallic dome, of radius R, of a Van de Graaff generator. A probe measures the electric field strength at various points outside the sphere surface. By what factor will the electric field value at the 2R distance be changed if the charge value were increased to (9/7)Q?
a.
(9/7)2
b.
9/7
c.
7/9
d.
(7/9)2
e.
9
10. A proton initially moves left to right long the x axis at a speed of 4.00 × 103 m/s. It moves into an electric field, which points in the negative x direction, and travels a distance of 0.400 m before coming to rest. What acceleration magnitude does the proton experience?
a.
4 × 103 m/s2
b.
2 × 107 m/s2
c.
1 × 109 m/s2
d.
8 × 1011 m/s2
e.
8 × 108 m/s2
11. Object A has a charge q on it, object B has a charge q on it, and object C has a charge 6q on it. These charges are arranged, one each, at the vertices of an equilateral triangle. Which charge has the greatest magnitude electric force on it?
a.
A
b.
B
c.
C
d.
All have equal magnitude forces on them.
e.
A and B
12. In a thundercloud there may be an electric charge of +30 C near the top of the cloud and 30 C near the bottom of the cloud. These charges are separated by about 3 km. What is the electric force between these two sets of charges? (ke = 8.99 × 109 N·m2/C2)
a.
0.9 × 104 N
b.
0.9 × 105 N
c.
0.9 × 106 N
d.
0.9 × 107 N
e.
0.9 × 108 N
13. Two identical balls have the same amount of charge, but the charge on ball A is positive and the charge on ball B is negative. The balls are placed on a smooth, level, frictionless table whose top is an insulator. Which of the following is true?
a.
Since the force on A is equal but opposite to the force on B, they will not move.
b.
They will move together with constant acceleration.
c.
Since the force on both balls is negative, they will move in the negative direction.
d.
None of the above is correct.
14. The electric field in a cathode ray tube is supposed to accelerate electrons from 0 to 1.6 × 107 m/s in a distance of 5.00 cm. What electric field is required? (me = 9.11 × 1031 kg and e = 1.60 × 1019 C)
a.
9,100 N/C
b.
23,300 N/C
c.
14,600 N/C
d.
29,200 N/C
e.
1,600 N/C
15. The beam of electrons that hits the screen of an oscilloscope is moved up and down by:
a.
gravity.
b.
a phosphorescent coating.
c.
varying the electron’s charge.
d.
electrical charges on deflecting plates.
1. When charging two objects by rubbing them together:
a.
Neither may be a conductor.
b.
They must be made of different material.
c.
They will sometimes end up with both being positively charged.
d.
The heat produced by friction is a necessary part of this process.
Explanation / Answer
You have asked a lot of questions at once. I have answered first 4 of these, including one numerical problem. You may post other questions separately.
1. B
2. C
3. B
4. E
We shall treat the concentrations as point charges. Then, the resultant field consists of two contributions, one due to each concentration.
The contribution due to the positive charge at 4000 m altitude is
E+ = kq/r^2
= (8.99 * 10^9 * 38 )/(1500)^2
= 151831.11 N/C downward
The contribution due to the negative charge at 1500 m altitude is
E- = kq/r^2
= (8.99 * 10^9 * 38 )/(1500)^2
= 151831.11 N/C downward
The resultant field is then E = E- + E+
= 151831.11 + 151831.11 N/C
= 303662.22 N/C
So, Option E.
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.