Chapter 22 Flashcards
(21 cards)
Three objects are brought close to each other, two at a time, When objects A and B are brought together, they repel. When objects B and C are brought together they also repel, which of the following is true
(a) Objects A and C possess charges of the same sign.
(b) Objects A and C possess charges of opposite sign.
(c) All three objects possess charges of the same sign.
(d) One object is neutral.
(e) Additional experiments must be performed todetermine the signs of the charges
a, c, e
Three objects are brought close to one another, two at a time. When objects A and B are brought together, they attract. When objects B and C are brought together, they repel. Which of the following are necessarily true?
(a) Objects A and C possess charges of the same sign.
(b) Objects A and C possess charges of opposite sign.
(c) All three objects possess charges of the same sign.
(d) One object is neutral.
(e) Additional experiments must be performed to determine information about the charges on the objects
b?, e
Object A has a charge of +2 C, and object B has a charge of +6 C. Which statement is true about the electric forces on the objects?
a) Fab = -3Fba
b) Fab = -Fba
c) 3Fab = -Fba
d) Fab = -Fba
e) Fab = Fba
f) 3Fab = Fba
b
What prevents gravity from pulling you through the ground to the center of the Earth? Choose the best answer.
1. The density of matter is too great.
2. The positive nuclei of your body’s atoms repel the positive nuclei of the atoms of the ground.
3. The density of the ground is greater than the density of your body.
4. Atoms are bound together by chemical bonds.
5. Electrons on the ground’s surface and the surface of your feet repel one another.
5
What happens when a charged insulator is placed near an uncharged metallic object?
1. They repel each other.
2. They attract each other.
3. They may attract or repel each other, depending on whether the charge on the insulator is positive or negative.
4. They exert no electrostatic force on each other.
5. The charged insulator always spontaneously
discharges
2
A metallic coin is given a positive electric charge. Itsmass:
1. increases measurably.
2. increases by an amount too small to measuredirectly.
3. remains unchanged.
4. decreases by an amount too small to measuredirectly.
5. decreases measurably
4
A metallic coin is given a negative electric charge. Itsmass:
1. increases measurably.
2. increases by an amount too small to measuredirectly.
3. remains unchanged.
4. decreases by an amount too small to measuredirectly.
5. decreases measurably
2
In the figure (q1, -q3 and q2) are in a line), assume the charged objects are fixed. Notice that there is no sightline from the location of q2 to the location of q1. If you were at q1, you wouldbe unable to see q2 because it is behind q3. How would you calculate theelectric force exerted on the object with charge q1
1. Find only the force exerted by q2 on charge q1.
2. Find only the force exerted by q3 on charge q1.
3. Add the force that q2 would exert by itself on charge q1 to the force thatq3 would exert by itself on charge q1.
4. Add the force that q3 would exert by itself to a certain fraction of theforce that q2 would exert by itself.
5. There is no definite way to find the force on charge
3
Two point charges attract each other with an electricforce of magnitude F. If one charge is reduced to one-third of its original value and the distance between the charges is doubled, what is the resulting magnitude ofthe electric force between them?
1. 1/12 F
2. 1/3 F
3. 1/6 F
4. 3/4 F
5. 3/2 F
1
The magnitude of the electric force between two protons is 2.30 × 10^-26 N. How far apart are they?
1. 0.100 m
2. 0.0220 m
3. 3.10 m
4. 0.00570 m
5. 0.480 m
1
Which of the following is not correct about electric charges?
a) There are two kind of electric charges; positive and negative.
b) Charges with the same sign attract one another.
c) Charges with opposite signs attract one another.
d) Electric charges are said to be quantized, which means they exist at integral multiples of a fundamental amount of charge.
e) Electric charge is always conserved in an isolated system. That is, when one object is rubbed against another, charge isnot created in the process. The electrified state is due to atransfer of charge from one object to the other
b
A test charge of +3C is at a point P where an external electric field is directed to the right and has a magnitude of 4 106 N/C. If the test charge is replaced withanother test charge of -3C, what happens to the external electric field at P?
(a) It is unaffected.
(b) It reverses direction.
(c) It changes in a way that cannot be determined.
a
Rank the magnitudes of the electric field at points A, B,and C shown in the figure (greatest magnitude first).
A
B
C
A free electron and a free proton are released inidentical electric fields. How do the magnitudes of the electric force exerted on the two particles compare?
1. It is millions of times greater for the electron.
2. It is thousands of times greater for the electron.
3. They are equal.
4. It is thousands of times smaller for the electron.
5. It is millions of times smaller for the electron.
3
A free electron and a free proton are released in identical electric fields. Compare the magnitudes of their accelerations.
1. It is millions of times greater for the electron.
2. It is thousands of times greater for the electron.
3. They are equal.
4. It is thousands of times smaller for the electron.
5. It is millions of times smaller for the electron.
2 (because the mass is much smaller)
A very small ball has a mass of 5.00 × 10-3 kg and a charge of 4.00 μC. What magnitude electric field directed upward will balance the weight of the ball sothat the ball is suspended motionless above the ground?
1. 8.21 × 102 N/C
2. 1.22 × 104 N/C
3. 2.00 × 1022 N/C
4. 5.11 × 106 N/C
5. 3.72 × 103 N/C
2
A circular ring of charge with radius b has total chargeq uniformly distributed around it. What is themagnitude of the electric field at the center of the ring?
1. 0
2. keq/b2
3. keq2/b2
4. keq2/b
5. none of those answers
1
An object with negative charge is placed in a region ofspace where the electric field is directed verticallyupward. What is the direction of the electric forceexerted on this charge?
1. It is up.
2. It is down.
3. There is no force.
4. The force can be in any direction.
2
The diagrams below show two uniformly charged spheres. Thecharge on the right sphere is 3 times as large as the charge on theleft sphere. Which force diagram best represents the magnitudesand directions of the electric forces on the two spheres?
they repel with same magnitude
The diagrams below show two uniformly charged spheres. The charge on theright sphere is 3 times as large as the charge on the left sphere. Each arrowrepresents the electric field at the center of one sphere created by the other.Which choice best represents the magnitudes and directions of the electricfield vectors created by one sphere at the location of the other sphere?
5
