FINAL EXAM Flashcards
a charged conductor is brought near an uncharged insulator. which of the following statements is true?
a. both objects will repel
b. both objects will attract
c. neither object exerts an electrical force on the other
d. the objects will repel each other only if the conductor has a negative charge
e. the objects will attract each other only if the conductor has a positive charge
b
both positive and negative charges attract a neutral object
consider 3 identical metal spheres, A, B, and C. sphere A carries a charge of -2.0uC; sphere B carries a charge of -6.0uC; and sphere C carries a charge of +4.0uC. spheres A and B are touched together and then separated. spheres B and C are then touched and separated. does sphere C end up with an excess or deficiency of electrons, and how many is it?
a. deficiency, 6x10^13
b. excess, 3x10^13
c. excess, 2x10^13
d. deficiency, 3x10^12
e. there is no excess or deficiency of electrons
e
all have -4uC
a -4.0uC charge is located 0.45m to the left of a +6.0uC charge. what is the magnitude and direction of the electrostatic force on the positive charge?
a. 2.2N to the right
b. 2.2N to the left
c. 1.1N to the right
d. 1.1N to the left
e. 4.4N to the right
d
an electron is located between the plates of a parallel-plate capacitor. what is the magnitude and direction of the electric field such that the electric force exactly balances the weight of the electron so that it remains stationary?
at what point(s) in the vicinity of the fixed charges shown could a third charge of +2q be placed so that the net electrostatic force on it would be zero?
a. somewhere on the x-axis to the right of the +4q charge
b. somewhere on the x-axis between the 2 charges, but nearer to the -2q charge
c. somewhere on the x-axis to the left of the -2q charge
d. somewhere on the x-axis between the 2 charges, but closer to the +4q charge
e. at 2 points along the x-axis, one such point is to the left of the -2q charge and the other is to the right of the +4q charge
c
complete the following statement: the electron-volt is a unit of
a. electric field
b. charge
c. energy
d. electric potential
e. electric force
c
measured in J
as an electron moves against an electric field,
a. its electrical potential decreases and its potential energy increases
b. its electrical potential increases and its potential energy increases
c. its electrical potential increases and its potential energy decreases
d. its electrical potential decreases and its potential energy decreases
e. its electrical potential remains constant and its potential energy increases
c
two point charges are held at the corners of a rectangle as shown in the figure. the rectangle has a height of 0.050m and a width of 0.150m. determine the electric potential at corner A.
what direction is the electric field at B?
towards D
what is the change in electric potential energy when a charge of -1.0uC is moved from A to F to C to E?
a. -7.0x10^-5J
b. 7.0x10^-5J
c. 3.0x10^-5J
d. -3.0x10^-5J
e. -4.0x10^-5J
b
EPE=qV
= q (Vf - Vi)
= (-1x10^-6)(-40-(30))
= 7.0x10^-5J
the potential difference across the ends of a wire is doubled in magnitude. which of the following statements concerning the resistance of the wire is true?
a. the resistance increases by a factor of 4
b. the resistance increases by a factor of 2
c. the resistance is not changed
d. the resistance decreases by a factor of 2
e. the resistance decreases by a factor of 4
c
R=p(L/A)
resistors in series have the same (voltage / current) through them
current
resistors in parallel have the same (voltage / current) across them
voltage
for resistors in parallel, the total resistance is (greater than / equal to / less than) the value of any single resistor
less than
what is the equivalent resistance of the circuit?
7.5
what is the current through the 1.8 resistor?
a. 3.3A
b. 2.8A
c. 14A
d. 6.9A
e. 5.6A
2.8A
Vbat=IR = 3.33A
I1.8 < Ibat, so must be b
what is the potential drop across the 3.5 resistor?
a. 17V
b. 25V
c. 8.0V
d. 2.0V
e. 5.0V
V = IR
(0.55)(3.6) = 2.0V
the length of a certain wire is kept the same while its radius is doubled. what is the change in resistance of the wire?
a. the resistance increases by a factor of 4
b. the resistance increases by a factor of 2
c. the resistance is not changed
d. the resistance decreases by a factor of 2
e. the resistance decreases by a factor of 4
e
A=πr^2
geometry and composition
a 4A current is maintained in a simple circuit with a total resistance of 2. how much energy is delivered in 45 seconds?
P=IV
V=IR = (4A)(2) = 8V
P= (4A)(8V) = 32W
P = energy/time
energy = Pt = (32J/s)(45s) = 1440J
2 resistors are connected in parallel, and the combination connected to a DC power supply with voltage V as shown. if the current shown is 2A, what is the value of the battery voltage?
6V
R=3
V=IR = (2A)(3) = 6V
Kirchhoff’s loop rule is a statement of
a. the law of conservation of momentum
b. the law of conservation of charge
c. the law of conservation of energy
d. the law of conservation of mass
e. Newton’s second law
c
which of the following equations corrected represents a use of Kirchhoff’s loop rule for the circuit shown?
a. 2V = (6)I3 + 6V + (12)I1
b. 4V = (8)I2 + (12)I1
c. 4V + 6V + (12)I1 = (8)I2
d. 4V + 6V = (12)I1 + (8)I2
e. none of these
d
which of the following statements concerning permanent magnets is false?
a. the North Pole of a permanent magnet is attracted to the South Pole
b. all permanent magnets are surrounded by a magnetic field
c. the direction of the magnetic field is indicated by the North Pole of a compass
d. magnetic field lines outside a permanent magnet originate from the north pole and the end on the south pole
e
no magnetic monopoles
two particles move through a uniform magnetic field as shown. which of the following statements concerning these particles is true?
a. the particles may both me neutral
b. particle 1 is positively charged, 2 negatively
c. particle 1 is positively changed, 2 positively
d. particle 1 is negatively charged, 2 negatively
e. particle 1 is negatively charged, 2 positively
d
both CCW - same sign charges