Final Exam Flashcards
A thin uncharged conducting spherical shell has a charge q carefully placed at its center through a small hole in the shell. The charge q does not touch the shell. What is the charge on the shell?
0
Wire A and Wire B are each carrying the same current. If the diameter of Wire A is twice that of Wire B, how does the drift velocity vdA in Wire A compare to that in Wire B?
VdA= VdB/4
The internal resistances of an ideal voltmeter and an ideal ammeter are respectively (ideal meaning the behavior of the system is not changed when using the meter)?
Infinite and zero
Increasing the separation of the two charged parallel plates of a capacitor, which are disconnected from a batter will produce what effect on the capacitor?
Decrease capacitance
In a certain material there is a current of 16 A flowing through a surface to the right, and there is an equal amount of positive and negative charge passing through the surface producing the current. How much negative charge passes through the surface?
8 C/s toward the left
An uncharged conductor is supported by an insulating stand. I pass a positively charged rod near the left end of the conductor, but do not touch it. The right end of the conductor will be:
Positive
Three resistors connected in series have individual voltages labeled Delta V1, Delta V2, and Delta V3, respectively. Which of the following expresses the value of the total voltage (delta Vt) taken over the three resistors together?
Delta VT= Delta V1+ Delta V2 + Delta V3
Which of the following characteristics are held in common by both gravitational and electrostatic forces when dealing with either point masses or charges?
All of the above
A resistor is connected to a battery with negligible internal resistance. If you replace the resistor with on e that has twice the resistance, by what factor does the power dissipated in the circuit change?
.50
Which is a unit of power?
J/s
A repelling force must occur between two charged objects under which conditions?
Charges are of like signs
If body M, with a positive charge, is used to charge body N by induction, what will be the nature of the charge left on the latter?
Must be negative
If body P, with a positive charge, is placed in contact with body Q (initially uncharged), what will be the nature of the charge left on Q?
Must be positive
I wish to use a positively charged rod to charge a ball by induction. Which statement is correct?
The ball must be a conductor
Electric field is dimensionally equivalent to which of the following?
N/C
The number of electric field lines passing through a unit cross sectional area is indicative of:
Field Strength
Relative distribution of charge density on the surface of a conducting solid depends on
The shape of the conductor
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?
None of the above is correct
If a charge +Q is placed inside a hollow isolated conductor that is originally neutral and the charge does not touch that conductor at any time:
The outside surface of the conductor will become positively charged
The Millikan oil-drop experiment demonstrated that
The electronic charge is quantized
In the Millikan oil-drop experiment, it was found that oil droplets
Could have positive, negative, or zero net charge.
The unit of electrical potential, the volt, is dimmensionally equivalent to
J/C
A free electron is in an electric field. With respect to the field, it experiences a force acting:
anti-parallel (in opposite direction)
In which case does an electric field do positive work on a charged particle?
A negative charge moves opposite to the direction of the electric field
Doubling the voltage across a parallel plate capacitor does not double which of the following?
The energy stored
You measure a 25.0 V potential difference across a 5.00 ohm resistor. What is the current flowing through it?
5.00A
If a certain resistor obeys Ohm’s law, its resistance will change
None of the above, since resistance is a constant for the given resistor
Two cylindrical resistors are made of the same material and have the same resistance. The resistors R1 and R2 have different radii, r1 and r2, and different lengths, L1 and L2. Which of the following relative values for radii and legths would result in equal resistances?
2r1=r2 and 4L1=L2
Which process will double the power given off by a resistor?
doubling the current by making a resistance half as big
A resistor is made of a material that has a resistivity that is proportional to the current going through it. If the voltage across the resistor is doubled, what happens to the power dissipated by it?
It increases by a factor of 2^3/2
When the voltage across a nonohmic resistor is doubled, the current through it triples. What happens to the power delivered to this resistor?
The power increases to 6 times the original amount
Doug rubs a piece of fur on a hard rubber rod, giving the rod a negative charge, what happens?
Electrons are added to the rod
A repelling force must occur between two charged objects under which conditions?
Charges are of like signs
When a glass rod is rubbed with silk which of the following statements best describe what happens
Electrons are removed from the rod
When charging two objects by rubbing them together
They must be made of different material
Who was the first to determine the electron’s charge
Millikan
An uncharged conductor is supported by an insulating stand. I pass the positively charged rod near the left end of the conductor but do not touch it. The right end of the conductor will be
Positive
Of the following substances, which one contains the highest density of free electrons?
Iron
Which of the following best characterizes electrical conductors?
Electric charges move freely
Which of the following best characterizes electrical insulators?
Charges on the surface don’t move
I wish to use a positively charged rod to charge a ball by induction. Which statement is correct?
The ball must be a conductor
How can an uncharged object attract an uncharged object made of non-conducting material
The charges in the uncharged object can become polarized
Two point charges are 4 cm apart. They are moved to a new separation of 2 cm. By what factor does the resulting mutual force between them change?
4
If the distance between two charges is tripled, the mutual force between them will be changed by what factor?
1/9
If the size of the charge value is tripled for both of two point charges maintained at a constant separation, the mutual force between them will be changed by what factor?
9.0
The constant Ke is equivalent dimmensionally to which of the following?
Nm^2/C^2
The beam of electrons that hits the screen of an oscilloscope is moved up and down by:
Electrical charges on deflecting plates
The electric field of a point charge has an inverse ____ behavior
r^2
The electric field at the surface of a positively charged conductor has a given direction characterized by which of the following?
zero vector
The electric field associated with a uniformly charged hollow metallic sphere is the greatest at:
The sphere’s outer surface
At what point is the charge per unit area greatest on the surface of an irregularly shaped conducting solid?
Where curvature is greatest
If a conductor is in electrostatic equilibrium near an electrical charge:
The electric field inside the conductor must be zero
The combination of two separated point charges of opposite sign but equal magnitude is called
dipole
A charge +Q is placed inside a balloon and the balloon is inflated. As the radius of the balloon r increases the number of field lines going through the surface of the balloon:
stays the same
The quantity of electrical potential, the volt, is dimensionally equivalent to:
electric field x distance
A free electron is in an electric field. With respect to the field, it experiences a force acting:
anti parallel
opposite in direction
In which case does an electric field do positive work on a charged particle?
a negative charge moves opposite to the direction of the electric field
The distance between two negative point charges is increased by a factor of three, the resultant potential energy is what factor times the initial potential energy?
1/3
Which of the following characteristics are held in common by both gravitational and electrostatic forces when dealing with either point masses or charges?
all of the above choices are valid
Consider two charged spheres one with +2 C and the other with -2C. A proton is at the point halfway between the spheres. What is not zero?
the force on the proton
At which location will the electric field between the tow parallel plates of a charged capacitor be the strongest in magnitude?
midway between the two plates, nearest their center
The unit of capacitance, the farad, is dimmensionally equivalent to which of the following?
C/V
Increasing the voltage across the two plates of a capacitor will produce what effect on the capacitor?
Decrease capacitance
If two parallel, conducting plates have equal positive charge, the electric field lines will:
leave both plates and go to infinity