Physics Final Study
An ordinary light bulb is marked "100 watt, 120 volt" It's resistance when on for a while is:
144 ohms
A uniform line of linear charge density = 5nC/m extends from x = 0 to x = 10 m. The magnitude of the electric field at x=12m is:
18.8 N/C
The electrostatic potential energy of the system of point charges -1, 2, and 3 at the corners of equilateral triangles whose side s = 50cm is:
18mI
The resistance of the unknown resistor R is:
2 ohms
The maximum E-component of an electromagnetic wave is 600 V/m, what is the maximum B-component?
2.0 x 10^-6 T
The magnetic flux through a certain coil is given by Om = (1/50pi)cos100pi*t. The units are S.I. The coil has 100 turns. The magnitude of the induced emf when t = 1/200 s is:
200V
A 3 ohm and a 6 ohm resistor are connected in parallel to a 12 V battery. What power is dissipated by the 6 ohm resistor?
24W
The electric potential in a region of space is given by V = 2xy+3y^2 in units of V. The electric field, in V/m in this region is
-2yi - (2x+6y)j
An infinite plane of surface charge density = +8.00nC/m^2 lies in the xy plane at the origin and a second that is -8nC/m^2 lies parallel to the yz plane at 4.00m. The electric field at 5m is approximate:
0
Points R and T are each distance d from each of two equal positive charges as shown. The work required to move a particle with charge q from R to T is:
0
Solid conducting sphere of radius r is placed concentrically inside conducting spherical shell of inner radius r01 and outer radius p2 The inner sphere carries a charge Q while the outer sphere does not carry any net charge The electric field for rb1 < r < rb2:
0
Two small spheres, each with a mass of m = 3.0g and charge q. Are suspended from a point by very light threads with L = 0.22m at 15 degrees
0.11 uC
An electric field is E = 400 N/C i for x > 0 and E = -400 i for x < 0 A gaussian cylinder of 30 cm length and radius 10 has a center at the origin, along the x axis one end at -15 and other at +15 What's the net charge?
0.22nC
A plastic rod of length L = 3.0m has a nonuniform linear charge density.... Lambda = cx Where c = 0.5 C/m^2. With V = 0 at infinity, with k being the Coulomb constant, what is the potential at point P = (0,y) with y = 4.0 m?
0.5k
Two solenoids are concentric. The inner solenoid has a radius of 5.0 cm and the outer one has a radius of 10cm. Each has a length of 50 cm and each has 200 turns of close packed copper wire .The mutual inductance of the two solenoids is
0.80 mH
A series circuit consists of a 40.0 V battery, a 40.0 ohm resistor, a 2.00 H inductor and an open switch. At t=0 s, the switch is closed. At some time later the current through the resistor is 0.400 A. At this time, at what rate is energy being stored in the magnetic field of the inductor?
09.6 W
The diagram shows four possible orientations of a dipole in the electric field, order the torque from least to greatest
1, 2, and 4 tie, then 3 (cross product)
You connect a 100 ohm resistor, an 800 mH inductor, and a 10.0 uF capacitor in series across a 60.0 Hz, 120 V (peak) source. The maximum current in the circuit is approximately
1.12 A
A capacitor in a flash camera is charged by a 1.5-V battery. When the camera flashes, this capacitor is discharged through an 8.3 kOhm resistor. The time constant of the circuit is 10ms. What is the value of the capacitance?
1.2 uF
A coaxial cable consists of a solid inner cylindrical conductor of radius 2.0mm and an outer cylindrical shell of inner radius 4.0 mm and outer radius 4.2 mm. A current of 20. A flows down the inner wire and an equal return current flows in the outer conductor. Find the magnetic field at a radius of 3.0 mm.
1.3mT
A 1.2-m radius cylindrical region contains a uniform electric field that is increasing uniformly with time. At t = 0 the field is 0 and at t = 5.0 s the field is 200 V/m. The total displacement current through a cross section of the region is:
1.6 x 10^-9 A
Charge is distributed uniformly along a very long straight wire. The electric field 2cm from the wire is 20N/C. The electric field 4cm from the wire is:
10 N/C
The potential difference between the ends of a 2-meter stick that is parallel to a uniform electric field is 200 V. The magnitude of the electric field is:
100 V/m
A capacitor in an LC oscillator has a maximum potential difference of 15 V and a maximum energy of 360 uJ. At a certain instant the energy in the capacitor is 40 uJ. At that instant, what is the emf induced in the inductor?
10V
A 110-V hair dryer is rated at 1200 W. What current will it draw when operating from a 110V electrical outlet?
11A
What is the magnetic field at the center of a circular loop with a diameter of 15.0 cm that carries a current of 1.50 A?
12.6 uT
Capacitors A and B are identical. Capacitor A is charged so it stores 4J of energy and capacitor B is uncharged. The capacitors are then connected in parallel. The total stored energy in the capacitors is now:
2J
A certain wire has resistance R. Another wire, of the same material, has half the length and half the diameter of the first wire. The resistance of the second wire is:
2R
Two large conducting plates are separated by a distance d, placed in a vacuum, and connected to a source of potential V. An oxygen ion, with charge 2e starts from rest on the surface of one plate and accelerates to the other. If e denotes the magnitude of the proton charge, the final kinetic energy of this particle is:
2eV
A parallel plate capacitor of separation distance d = 5.0mm, has a dielectric slab of thickness b = 2.0mm and dielectric constant K = 2.0. The capacitor is connected to a 12V source. What is the magnitude of the electric field in the gap between the dielectric and the top plate?
3.0 kV/m
Charge is distributed uniformly on the surface of a very large flat conducting plate. The electric field 2cm from the place is 30N/C. The electric field 4cm from the plate is:
30 N/C
The emf and the internal resistance of a battery are as shown in the figure. When the terminal voltage Vab is equal to 15.0V, what is the current through the battery?
31V 2ohm - 8A
You connect three capacitors as shown in the diagram C1 = 2uf C2 = 4uf C3 = 12uF. A potential difference of 9.0 V is maintained between the terminals A and B. The magnitude of the charge on capacitor C3 is approximately:
36uC
In an oscillating LC circuit, the total stored energy is U and the maximum charge on the capacitor is Q. When the charge on the capacitor is Q/2, the energy stored in the inductor is:
3U/4
What is the power dissipated in the 16 ohm resistor in the circuit below?
4.0 W
An electron passes through a region where there is an electric field of 4.0 x 10^5 V/m and a magnetic field of 0.090 T. The directions of the magnetic field, the electric field and electron velocity are mutually perpendicular. If the electron is not deflected from its straight line path, it's velocity must be:
4.4 x 10^6 m/s
A metal sphere carries a charge of 2.5 x 10-9 C and is at a potential of 400V. Relative to the potential far away the potential at the center of the sphere is:
400V
Radio receivers are usually tuned by adjusting the capacitance of an LC circuit. If C = C1 allows you to receive a 1600 kHz station, then for a 800 kHz station, you must adjust C to:
4C1
You connect a 100 ohm resistor, an 800 mH inductor, and a 10.0 uF capacitor in series across a 60.0 Hz, 120V (peak) source. The resonant frequency of your circuit is approximately
56 Hz
A coil has a resistance of 80 ohms and an impedance of 100 ohms. Its reactance in ohms is:
60
The current in the 2 ohm resistor is 3 A. What is the potential difference across the 3 ohm resistor?
6V
The heater element of a particular 120V toaster is a 8.9m length of nichrome wire., whose diameter is 0.86mm. The resistivity of nichrome at the operating temperature of the toaster is 1.3x10-6 ohm meters. If the toaster is operated at a voltage of 120V, how much power does it draw?
720W
A wire rod rolls with a speed of 20 m/s on two metallic rails, 1.0 m apart, that form a closed loop. If the magnetic field is 1.5 T into the page, the power dissipated in the resistor R and the current direction are, respectively,
76 mW, clockwise
A capacitor C1 = 4.0uF is charged to 12.0V. It is then connected to an uncharged capacitor, C2 = 2.0uF. The voltage across C1 after equilibrium is reached is:
8.0V
A charged capacitor is being discharged through a resistor. At the end of one time constant, the charge has been reduced by (1-⅓) = 63% of it's initial value. At the end of two time constants, the charge has been reduced by what percent of its initial value?
86%
The rapid decay of charge in just a few cycles on the capacitor in an undriven RLC circuit might be due to:
A large resistance
The diagram shows the electric field lines due to two charged parallel metal plates. We conclude that:
A proton at X would experience the same force if it were placed at Y.
A device used chiefly for storing energy in a magnetic field is
An inductor
An electromagnetic wave is generated by:
Any accelerating charge
Two small spheres attract one another electrostatically. This can occur for a variety of reasons. Which of the following statements must be true?
At least one sphere is charged.
A certain battery is rated at 80 Ah. An ampere-hour is a unit of:
Charge
In Ampere's law (integration) the integration must be over any:
Closed path
The sum of the currents into a junction equals the sum of the currents out of the junction is a consequence of:
Conservation of charge
A long straight wire is in the plane of a rectangular conducting loop. The straight wire carries an increasing current in the direction shown. The current in the rectangle is:
Counterclockwise
Two wires are made of the same material and have the same length but different radii. They are joined end to end and a potential difference is maintained across the combination. Of the following the quantity that must be the same for both wires is:
Current
An electron moves north in a region where the magnetic field points down. The magnetic force on the electron is:
East
The electron volt is a unit of:
Energy
In the diagrams, all light bulbs are identical and all emf devices are identical. In which circuit (I, II, III, IV, V) will the bulbs be dimmest (have the least current) ?
IV
When switch S is open, the ammeter in the circuit shown reads 2.0 A. When S is closed, the ammeter reading:
Increases slightly
Pulling the plates of an isolated charged parallel plate capacitor apart:
Increases the potential differences
In a sinusoidally driven series RLC circuit, the current leads the applied emf. The rate at which energy is dissipated in the resistor can be increased by:
Increasing the capacitance and making no other changes
Two charged metal spheres are connected by a wire. Sphere A is larger than sphere B as shown. The magnitude of the electrical potential of sphere A:
Is the same as that at the surface of sphere B
What happens to the electric potential energy of a positive charge when it is released from rest in a region of space where there is a uniform electric field?
It will decrease because the charge will move in the direction of the field.
A toroid with a square cross section carries current I. The magnetic field has its largest magnitude:
Just inside the toroid at its inner surface
An RL series circuit is connected to an emf source having angular frequency theta. The current:
Lags the source emf by tan^-1(theta L/R)
The magnetic torque exerted on a flat current-carrying loop of wire by a uniform magnetic field 4 is:
Misprint, 4 supposed to be B with arrow above it (misprint) Maximum when the plane of the loop is parallel to 4
When a positive charge is released from rest in a region of space where there is a uniform electric field it will:
Move at a constant acceleration
Magnetism is produced by
Movement of electric charged particles
A conductor is distinguished from an insulator by the number of
Nearly free electrons
In the circuit shown, there will be a non-zero reading in galvanometer G:
Only just after S is opened or closed
IN a certain region of space, the electric potential decreases uniformly from Easy to West and does not vary in any other direction. The electric field:
Points West and does not vary with position
An electromagnetic wave is transporting energy in the positive y direction. At one point and one instant the magnetic field is in the positive x direction. The electric field at that point and instant is:
Positive z direction
A cylindrical region of radius R contains a uniform magnetic field, parallel to its axis with magnitude that is changing linearly with time. If r is the radial distance from the cylinder axis, the magnitude of the induced electric field inside the cylinder is proportional to:
R
In each of the following operations, energy is expended, the LEAST percentage of returnable electrical energy will be yielded by:
Sending a current through a resistor
A charged capacitor and an inductor are connected in series. At time t = 0 the current is zero, but the capacitor is charged. If T is the period of the resulting oscillations, the next time, after t = 0 that the current is a maximum is:
T/4
A dielectric slab is slowly inserted between the plates of a parallel plate capacitor, while the potential difference between the plates is held constant by a battery. As it is being inserted:
The capacitance and the charge on the plate increase
A uniform magnetic field is directed into the page. A charged particle, moving in the place of the page, follows a clockwise spiral of decreasing radius as shown. A reasonable explanation is:
The charge is negative and slowing down
If the charge on a parallel plate capacitor is doubled:
The electric field is doubled
When a rubber rod is given a negative charge by rubbing it with fur
The fur becomes positive
The switch S is initially at position a for a long time, It is then switched to position b. Describe what happens to the light bulb as a function of time when the switch is flipped from a to b?
The light bulb was off. It then lights up but the brightness decreases with time and eventually goes off.
A series circuit consists of a battery, a light bulb, an inductor, and a switch. The time constant for the RL circuit is of the order of a few seconds. What happens to the light bulb when switch S is closed?
The light comes on gradually in a few seconds and stays on.
Which of the following statements contradicts one of Maxwells equations?
The net magnetic flux through a closed surface depends on the current inside
Two of Maxwell's equations contain a path integral on the left side and an area integral on the right side. For them:
The path must be the boundary of the area
A point particle with charge q is placed in the center of a spherical gaussian surface. The electric flux is changed if:
The point charge is moved to just outside the sphere
The primary of an ideal transformer has 100 turns and the secondary has 500 turns. Then:
The primary current is five times the secondary current
The charge on each capacitor in a set of capacitors in series is:
The same
Particles 1 with a charge q1 and 2 with charge q2 are on the x-axis q1 at x=a and q2 x=-2a
The third particle at the origin is 4q1 Same field as found by b experimenter q vs 2q
Faraday's law states that an induced emf is proportional to:
The time rate of change of the magnetic flux
The concept of difference in electric potential is most closely associated with:
The work per unit quantity of charge
Magnetic field lines inside the solenoid shown are:
Toward the top of the page
An electron traveling west enters a region where the electric field is uniform and points north, the electron:
Veers south
A magnetic field exists between the plates of a capacitor:
While the capacitor is being charged or discharged
Solid conducting sphere of radius r is placed concentrically inside conducting spherical shell of inner radius r01 and outer radius p2 The inner sphere carries a charge Q while the outer sphere does not carry any net charge The electric field for r > rb2 is :
kQ / r^2
Solid conducting sphere of radius r is placed concentrically inside conducting spherical shell of inner radius r01 and outer radius p2 The inner sphere carries a charge Q while the outer sphere does not carry any net charge The electric field for rs < r < rs1 is:
kQ/r^2
Two isolated concentric, thin metal spherical shells have radii a and b as shown. The inner shell has an excess charge Q1 and the outer shell has an excess charge Q2. Both positive. With V=0 at infinity, what is the electric potential at a distance r where r<a?
kQ1/a + kQ2/b
The radius of curvature of the path of a charged particle moving perpendicular to a magnetic field is given by:
mv/(qB)
An infinite slab of thickness 2d lies in the xz plane. The slab has a uniform volume charge density p. Using symmetry and Gauss's Law show that the electric field where 0 < y < d
py/e0
A point particle with charge q is at the center of a Gaussian surface in the form of a cube. The electric flux through any one face of the cube is:
q/6eo
