Physic II Final

60 flashcards · Physics · by Nini Huynh

1: positive; 2: negative
A very long straight wire has charge per unit length1.52 × 10-10 C/m. At what distance from the wire is the magnitude of the electric field equal to 2.40 N/C?
1.14m
Consider the point charges q1 and q2 in the picture below. What is the directions of electric field at point O due to i) q1 ii) q2 iii) both charges (the sum of both fields)?
i) left ii) left iii) left
A spherical cavity is hollowed out of the interior of a neutral conducting sphere. At the center of the cavity is a positive point charge q. What is the total surface charge on the interior surface (i.e., on the wall of the cavity) and exterior surface of the conductor, respectively?
-q and +q
A spherical cavity is hollowed out of the interior of a neutral conducting sphere. At the center of the cavity is a positive point charge q. What is the magnitude of the electric field at distance r from the center between the inner surface and outer surface of the conductor?
zero
A conductor with an inner cavity, like that shown in the picture, is charged a positive charge of +4.80 nC. Then a point charge -5.80 nC is placed within the cavity, insulated from the conductor. How much charge is i) on the inner surface of the conductor ii) within the conductor iii) on the outer surface of the conductor?
i) +5.8 nC ii) zero iii) -1.00 nC
A conductor with an inner cavity, like that shown in the picture, is charged a positive charge of +4.80 nC. Then a point charge -5.80 nC is placed within the cavity, insulated from the conductor. What is the direction of the electric field on the outer surface of the conductor?
perpendicular to the surface and inward
The dashed lines in the diagram below represent cross sections of equipotential surfaces drawn in 1 increments. What is the work done by the electric force to move a 1 C charge from i) A to B ii) A to D?
i) zero ii) 1 J
A metal sphere with radius ra is supported on an insulating stand at the center of a hollow, metal spherical shell with radius rb. There is charge on the inner sphere and charge on the outer spherical shell as shown below. Take the potential to be zero when the distance from the center of the spheres is infinite. What is the potential V(r) at distance ra<r<rb?
A metal sphere with radius ra is supported on an insulating stand at the center of a hollow, metal spherical shell with radius rb. There is charge on the inner sphere and charge on the outer spherical shell as shown below. Take the potential to be zero when the distance from the center of the spheres is infinite. What is the potential V(r) at distance r>rb?
V(r) = 0
Find the energy U of a capacitor in terms of C and Q by using the definition of capacitance and the formula for the energy in a capacitor. Answer must be in terms of C and Q.
Consider the combination of capacitors shown in the figure below. Th e charge on plate 1 is +Q. What are the charges of plates 3 and 6?
+Q and -Q
For the capacitor network shown in the figure, the potential difference across ab is 220 V. What is the total charge stored in this network?
A metallic wire has a diameter of 4.12 mm. When the current in the wire is 8.00 A, the drift velocity is 5.4 ⨉ 10-5 m/s. What is the density of free electrons in the meal? Charge of electron is 1.6 ⨉ 10-19 C. Watch for units!
6.9 x 1028 m-3
A single resistor is wired to a battery as shown in the diagram on the left below. Define the total power dissipated by this circuit as P0. Now, a second identical resistor is wired in series with the first resistor as shown in the second diagram to the right. What is the power dissipated by the circuit on the right in terms of P0?
When switch S in the figure is open, the voltmeter V of the battery reads 3.10 V. When the switch is closed, the voltmeter’s reading drops to 2.92 , and the ammeter A reads 1.60 A. Assume that the two meters are ideal, so they do not affect the circuit. What is the emf E of the battery?
3.10 V
2 & 3
For the combination of resistors shown, what is the equivalent resistance between points A and B?
5 Ω
A capacitor with capacitance C is initially charged with charge Q. At time t = 0, a switch is thrown to close the circuit connecting the capacitor in series with a resistor of resistance R. What happens to the charge on the capacitor immediately after the switch is thrown?
The electrons on the negative plate eventually pass through the resistor and neutralize the charge on the positive plate.
A capacitor with capacitance C is initially charged with charge Q. At time t = 0, a switch is thrown to close the circuit connecting the capacitor in series with a resistor of resistance R. What is the current that flows through the resistor immediately after the switch is thrown?
A coil with magnetic moment 1.46 A.m2 is oriented initially with its magnetic moment antiparallel to a uniform magnetic field of magnitude 0.800 T. What is the change in potential energy of the coil when it is rotated 180 degrees, so that its magnetic moment is parallel to the field?
-2.34 J
-y direction
The electron moves along a helical path about an axis parallel to the field lines with constant radius and constant velocity in the x direction.
A particle with a charge of -1.24 x 10-8 C is moving with with velocity v = 4.19 x 104 m.s i - 3.85 x 104 m/s j. What is the force exerted on this particle by magneticF field B = 1.90 t i?
Fx,Fy,Fz = 0,0, -9.07 x 10-4 N
A circular area with a radius of 6.00 m lies in the xy plane. What is the magnitude of the magnetic flux through this circle due to a uniform magnetic field with a magnitude of 0.200 T in the +z direction?
22.6 Wb
Four very long, current-carrying wires in the same plane intersect to form a square with side lengths of 37.0 cm, as shown in the figure. The currents running through the wires are 8.0 A, 20.0 A, 10.0 A, and I. In what direction should the current I be to make the magnetic field at the center of the square zero?
downward
Consider a very long solenoid. A segment of length L and diameter D of such a solenoid is shown in the figure. The solenoid has n turns per unit length and carries current I. Which figure shows the loop that must be used as the Ampèrean loop for finding the magnetic field inside the solenoid?
B
An electron moves with velocity as shown in the figure. What is the direction of the magnetic field this electron produces at points A, B, C, and D, respectively?
out of the paper at A, out of the paper at B, out of the paper at C, the field is zero at D
Two long, straight, parallel wires, 10.0 cm apart carry equal 4.00 A currents in the same direction, as shown in the figure .What is the magnitude of the magnetic field at the point midway between the wires?
0 T
0 T.m, -5.7 x 10-6 T.m, 1.3 x 10-6 T.m
A single loop of wire with an area of 0.600 m2 is in a uniform magnetic field that has an initial value of 3.80 T, is perpendicular to the plane of the loop, and is decreasing at a constant rate of 0.220 T/s. What emf is induced in this loop?
1.32 x 10-2 V
A circular loop of wire is in a region of spatially uniform magnetic field, as shown in the figure. The magnetic field is directed into the plane of the figure. What is the direction of the induced current in the loop when B is increasing?
Counterclockwise
A rectangle measuring 30.0 cm by 40.0 cm is located inside a region of a spatially uniform magnetic field of 1.50 T, with the field perpendicular to the plane of the coil (the figure). The coil is pulled out a steady rate of 2.00 cm/s traveling perpendicular to the field lines. the region of the field ends abruptly as shown. What induced emf is in the coil 1) when coil is all inside the field 2) when coil is all outside the field?
1) 0V 2) 0 V
What inductance would be needed to store 1.08 x 107 J of energy in a coil carrying current of 300 A?
240 H
The inductor shown in figure has inductance L and carries a current in the direction shown. The current is changing at a constant rate. The potential Vab between points a and b is 1.04 V, with point a at higher potential. How must the current be changing?
Current is decreasing
An L-R-C series circuit (with DC current) has L = 0.480 H, C = 2.7 x 10-5 F and a resistor R. What is the angular frequency of the circuit when R = 0?
278 rad/s
Consider a series L-R-C circuit with AC current. What happens to the resonance angular frequency ω0 of the circuit, if we keep the values of R and C constant but double the value of L?
An L-R-C circuit, operating 60 Hz (frequency, f, of an AC current), has an inductor with an inductance of 1.53 x 10-3 H, a capacitance of 1.67 x 10-2 F, and a resistance of 0.329 Ω. What are the inductive reactance, the capacitive reactance and the impedance of this circuit, respectively?
0.577 Ω, 0.159 Ω, 0.532 Ω
An AC source drives a sinusoidal current of amplitude I0 and frequency ω into an inductor having inductance L and a capacitor having capacitance C that are connected in series. The current as a function of time is given by I(t) = I0sinωt. If VL and VC are the voltages across the inductor and capacitor and IL and IC are their respective currents, which of the following statements is true?
VL leads IL and VC lags IC.
The primary coil of a transformer contains 200 turns; the secondary has 200 turns. The primary coil is connected to a size AA battery that supplies a constant voltage of 1.5 volts. What voltage would be measured across the secondary coil?
Zero
What is the wavelength λ for gamma rays of frequency f = 6.90 x 1021 Hz in nanometers? (1nm = 10-9 m)
4.35 x 10-5 nm
The electric and magnetic field vectors at a specific point in space and time of an electromagnetic wave are illustrated in the figure. In what direction does the electromagnetic wave propagate?
+z
A and D