PHYS1304 Chapters 29, 30,31, 32, and 33
When an RL circuit is connected to a battery, which is true about its initial and final states? It initially acts like a broken wire and finally acts like ordinary connecting wire. It initially acts like ordinary connecting wire and finally acts like a broken wire. It acts like broken wire throughout the charging. It acts like ordinary connecting wire throughout the charging.
It initially acts like a broken wire and finally acts like ordinary connecting wire.
Which describes the magnetic flux through a section of a loop? It is a vector that is directed outward through the section. It is a vector that is directed inward through the section. It is a vector that is tangent to the section. It is a scalar.
It is a scalar.
Which describes the integration in Ampere's law? It is an integration across the diameter of a loop. It is an integration around the circumference of a loop. It is an integration across the area of a loop.
It is an integration around the circumference of a loop.
In the demonstration where a loop is pulled out of a magnetic field at constant speed, which is true about the power of your force? It is greater than the power of dissipation by the current. It is less than the power of dissipation by the current. It is equal to the power of dissipation by the current.
It is equal to the power of dissipation by the current.
Which is true about the emf induced in a loop by a magnet? It is equal to the inverse of the rate at which the magnetic flux through the loop changes. It is equal to the magnetic flux through the loop. It is equal to the rate at which the magnetic flux through the loop changes. It is equal to the inverse of the magnetic flux through the loop.
It is equal to the rate at which the magnetic flux through the loop changes.
Which is true about the inductance of an inductor? It is equal to the product of the current and the magnetic flux linkage. It is equal to the ratio of the magnetic flux linkage to the current. It is equal to the ratio of the current to the magnetic flux linkage.
It is equal to the ratio of the magnetic flux linkage to the current.
We measure the magnetic field near a current-carrying wire that extends a long distance, both above and below the level of the measurement. Then we remove the bottom section of the wire (the section below the level of measurement). What happens to the magnitude of the magnetic field at the point of measurement? It is halved. It remains the same. It is doubled.
It is halved.
The current though an inductor decreases at a certain rate. Which is true about the self-induced emf of the inductor? It is in the direction of the current so as to oppose the decrease. It is in the direction opposite that of the current so as to oppose the decrease. It is in the direction of the current so as to aid the decrease. It is in the direction opposite that of the current so as to aid the decrease. It is zero.
It is in the direction of the current so as to oppose the decrease.
The current though an inductor increases at a certain rate. Which is true about the self-induced emf of the inductor? It is in the direction of the current so as to oppose the increase. It is in the direction opposite that of the current so as to oppose the increase. It is in the direction of the current so as to aid the increase. It is in the direction opposite that of the current so as to aid the increase. It is zero.
It is in the direction opposite that of the current so as to oppose the increase.
When an RL circuit is connected to a battery, what happens to the current in the circuit? It is initially at its maximum value and then decreases exponentially with time. It is initially at its maximum value and then decreases linearly with time. It is initially 0 and then increases exponentially with time. It is initially 0 and then increases linearly with time. It is constant during the charging.
It is initially 0 and then increases exponentially with time.
When an RL circuit is connected to a battery, what happens to the potential difference across the resistor? It is initially at its maximum value and then decreases exponentially with time. It is initially 0 and then increases. It is constant. It is initially at its maximum value and then decreases linearly with time.
It is initially 0 and then increases.
When an RL circuit is connected to a battery, what happens to the potential difference across the inductor? It is initially 0 and then increases. It is initially at its maximum value and then decreases linearly with time. It is initially at its maximum value and then decreases exponentially with time. It is constant.
It is initially at its maximum value and then decreases exponentially with time.
Which is true about the magnitude of the magnetic field inside a toroid? It is inversely proportional to the radius. It is independent of the radius. It is proportional to the radius.
It is inversely proportional to the radius.
In the demonstration where a magnet is brought near a loop, which is true about the induced current if we move the magnet faster? It is smaller and in the same direction as before. It is larger and in the same direction as before. The size and the direction are the same. It is now smaller and in the opposite direction. It is now larger and in the opposite direction. The size is the same but the current is now reversed.
It is larger and in the same direction as before.
When the charge in the capacitor is zero, which is true about the current in the inductor? It is maximum. It is half maximum. It is one-fourth maximum. It is zero.
It is maximum.
When the electric field magnitude in the capacitor is zero, which is true about the magnetic field magnitude in the inductor? It is maximum. It is half maximum. It is one-fourth maximum. It is zero.
It is maximum.
When the magnetic field magnitude in the inductor is zero, which is true about the electric field magnitude in the capacitor? It is one-fourth maximum. It is zero. It is maximum. It is half maximum.
It is maximum.
We draw an Amperian loop within a wire that carries current uniformly across its circular cross-sectional area. Which describes the amount of current encircled by the Amperian loop? It is proportional to the circumference of the loop. It is inversely proportional to the circumference of the loop. It is proportional to the area of the loop. It is inversely proportional to the area of the loop.
It is proportional to the area of the loop.
We draw an Amperian loop within a wire that carries current uniformly across its circular cross-sectional area. Which describes the value of the integral in Ampere's law? It is proportional to the total current. It is inversely proportional to the total current. It is proportional to the current encircled by the loop. It is inversely proportional to the current encircled by the loop. It is proportional to the current that is outside the loop. It is inversely proportional to the current that is outside the loop.
It is proportional to the current encircled by the loop.
Which is true about the magnitude of the magnetic field inside a toroid? It is proportional to the current. It is inversely proportional to the current. It is independent of the current.
It is proportional to the current.
Which is true about the self-induced emf of an inductor? It is inversely proportional to the inductance. It is independent of the inductance. It is proportional to the inductance.
It is proportional to the inductance.
Which is true about the magnitude of the magnetic field inside a toroid? It is inversely proportional to the number of turns. It is independent of the number of turns. It is proportional to the number of turns.
It is proportional to the number of turns.
In the discussion about pulling the loop from the magnetic field, why does the flux change? The magnitude of the magnetic field is decreased. The magnitude of the magnetic field is increased. The area through which the magnetic field pierces is increased. The area through which the magnetic field pierces is decreased.
The area through which the magnetic field pierces is decreased.
If the self-induced emf of an inductor is zero, which is true about the current through it? The current is increasing. The current is decreasing. The current is constant or zero.
The current is constant or zero.
Which describes the magnetic field along the central axis of a current loop? The field is directed along the axis and toward the loop on both sides of the loop. The field is directed along the axis and away from the loop on one side and toward the loop on the other side. The field is perpendicular to the axis. The field is directed along the axis and away from the loop on both sides of the loop.
The field is directed along the axis and away from the loop on one side and toward the loop on the other side.
In an ideal LC oscillator, which is true about the oscillations of the electric field and the magnetic field? They are in phase. They are out of phase by 90º (or ¼ oscillation). They are out of phase by 180º (or ½ oscillation). They out of phase by 360º (or 1 full oscillation).
They are out of phase by 180º (or ½ oscillation).
Which describes the magnetic field vectors near a long straight wire carrying current? They are tangent to concentric circles around the wire, in a plane perpendicular to the wire. They are perpendicular to the wire, directed toward it. They are parallel to the wire, in the direction of the current. They are parallel to the wire, in the direction opposite that of the current. They are perpendicular to the wire, directed away from it.
They are tangent to concentric circles around the wire, in a plane perpendicular to the wire.
Which describes the magnetic field lines of a current loop? They extend away from the loop on both sides of the loop. They extend toward the loop on both sides of the loop. They extend toward the loop on one side and away from the loop on the other side.
They extend toward the loop on one side and away from the loop on the other side.
Which describes the magnetic field lines near a long straight wire carrying current? They are perpendicular to the wire and extend away from it. They are perpendicular to the wire and extend toward it. They are parallel to the wire, in the direction of the current. They are parallel to the wire, in the direction opposite that of the current. They form concentric circles around the wire, in a plane perpendicular to the wire.
They form concentric circles around the wire, in a plane perpendicular to the wire.
Which describes the procedure for finding the magnetic field on the central axis of a current loop due to the elements on the loop? We sum the magnitudes of the magnetic fields. We sum the field components that are perpendicular to the central axis. We sum the field components that are parallel to the central axis.
We sum the field components that are parallel to the central axis.
Which currents are included in a calculation of Ampere's law? only currents that are outside the loop of integration only currents that are inside the loop of integration only currents that are perpendicular to the plane of the loop of integration only currents that are parallel to the plane of the loop of integration
only currents that are inside the loop of integration
A loop lies in a magnetic field, with the field perpendicular to the plane of the loop. Which does not induce a current in the loop? increasing the magnitude of the field increasing the size of the loop rotating the loop around a diameter sliding the loop perpendicular to the field vectors changing the direction of the field
sliding the loop perpendicular to the field vectors
What do we calculate if we integrate length element ds around a full circle? the radius of the circle the diameter of the circle the area of the circle the circumference of the circle
the circumference of the circle
n Ampere's law, when we integrate the magnetic field along a loop, which are summing? the magnitudes of the field vectors at every point along the loop the field components that are perpendicular to the path elements, at every point along the loop the field components that are parallel to the path elements, at every point along the loop
the field components that are parallel to the path elements, at every point along the loop
In the demonstration where a magnet is brought near a loop, what determines the induced current? the rate at which the number of magnetic field lines intercepted by the loop changes the spacing of the magnetic field lines intercepted by the loop the strength of the magnetic field intercepted by the loop the number of magnetic field lines intercepted by the loop
the rate at which the number of magnetic field lines intercepted by the loop changes
When an RL circuit is connected to a battery, what percent of the final current appears at the end of the first time constant? 25% 50% 63% 100%
63%
A long straight wire carries current. What is the angle between the direction of the current and the direction of the magnetic field at a point near the wire? 0º 180º 90º
90º
Which is true? A changing magnetic field produces a constant perpendicular magnetic field. A changing magnetic field produces a changing perpendicular magnetic field. A changing magnetic field produces a constant parallel magnetic field. A changing magnetic field produces a changing parallel magnetic field. A changing magnetic field produces an electric field.
A changing magnetic field produces an electric field.
In the discussion about pulling the loop from the magnetic field, what force opposes our pull on the loop? An electric force on the sides parallel to the motion. An electric force on the opposite side of the loop. An electric force on the sides parallel to the motion and on the opposite side of the loop. A magnetic force on the sides parallel to the motion. A magnetic force on the opposite side of the loop. A magnetic force on the sides parallel to the motion and on the opposite side of the loop.
A magnetic force on the opposite side of the loop.
Which is true about the magnetic field lines of a solenoid? Internally, they are widely spaced with a uniform spacing. Externally, they are more closely spaced with a uniform spacing. Internally, they are widely spaced with a nonuniform spacing. Externally, they are more closely spaced with a uniform spacing. Internally, they are closely spaced with a nonuniform spacing. Externally, they are more widely spaced with a uniform spacing. Internally, they are closely spaced with a uniform spacing. Externally, they are more widely spaced with a nonuniform spacing.
Internally, they are closely spaced with a uniform spacing. Externally, they are more widely spaced with a nonuniform spacing.
Which is true about the potential energy stored in an inductor? It depends on the current and the inductance. It depends on the self-induced emf but not the current. It depends on the current but not the inductance. It depends on the inductance but not the current. It depends on the self-induced emf but not the inductance.
It depends on the current and the inductance.
Which is true about the potential energy stored in an inductor? It depends on the self-induced emf. It depends on the inverse of the self-induced emf. It depends on the current. It depends on the inverse of the current.
It depends on the current.
Which is true about the energy density of a magnetic field? It depends on neither the field magnitude nor field direction. It depends on the field magnitude but not the field direction. It depends on both the field magnitude and direction. It depends on the field direction but not the field magnitude.
It depends on the field magnitude but not the field direction.
Which is true about the potential energy stored in an inductor? It depends on the inductance. It depends on the inverse of the inductance. It depends on the self-induced emf. It depends on the inverse of the self-induced emf.
It depends on the inductance.
Which is true about the inductance of a solenoid? It depends on the number of turns per unit length and the area of each turn. It depends on the number of turns per unit length but not on the area of each turn. It depends on the area of each turn but not on the number of turns per unit length.
It depends on the number of turns per unit length and the area of each turn.
When a conducting plate swings through a magnetic field, which is true? Energy is transferred from mechanical energy to the magnetic field. Energy is transferred from the magnetic field to thermal energy. Energy is transferred from mechanical energy to thermal energy and then back to mechanical energy. Energy is transferred from the magnetic field to mechanical energy. Energy is transferred from mechanical energy to thermal energy.
Energy is transferred from mechanical energy to thermal energy.
Which is true about the self-induced emf of an inductor? It depends on the amount of current through the inductor. It is a fixed value, depending on only the geometry of the device. It depends on the rate at which the current through it is changing. It depends on the rate of dissipation.
It depends on the rate at which the current through it is changing.
When an RL circuit is connected to a battery, what happens to the net potential difference around the full circuit loop? It decreases exponentially with time. It does not change. It increases exponentially with time.
It does not change.
The current though an inductor increases at a certain rate. Which is true about the self-induced emf of the inductor? It decreases at a constant rate. It is zero. It increases in proportion to the current. It has a constant, nonzero value.
It has a constant, nonzero value.
If two parallel currents attract each other, which describes the directions of the currents? They are in the same direction. They are in opposite directions. They can be in either the same direction or in opposite directions, depending on the relative sizes of the currents.
They are in the same direction.
Which is true? Electric potential is associated with electric fields due to static charges but not with induced electric fields. Electric potential is associated with both electric fields due to static charges and induced electric fields. Electric potential is associated with induced electric fields but not with electric fields due to static charges. Electric potential is associated with both electric fields due to static charges and magnetic fields. Electric potential is associated with magnetic fields but not with electric fields due to static charges.
Electric potential is associated with electric fields due to static charges but not with induced electric fields.
In the Biot-Savart law, which describes angle θ? It is the angle between a current-length element and the magnetic field created by that element. It is the angle between the magnetic field created by a current-length element and a vector directed from that element to the point of measurement. It is the angle between the direction of the current in a current-length element and a vector directed from that element toward the point of measurement.
It is the angle between the direction of the current in a current-length element and a vector directed from that element toward the point of measurement.
Which describes the vector calculation of the magnetic flux through a section of a loop? It is the cross product of the magnetic field and the section's area vector. It is the ratio of the section's area to the magnetic field magnitude. It is the ratio of the magnetic field magnitude to the section's area. It is the dot product of the magnetic field and the section's area vector.
It is the dot product of the magnetic field and the section's area vector.
In the demonstration where a loop is pulled out of a magnetic field, which gives the power of your pull? It is the product of your force and the speed at which the loop moves. It is the ratio of your force to the speed at which the loop moves. It is the ratio of the speed at which the loop moves to your force.
It is the product of your force and the speed at which the loop moves.
Which is the energy density of a magnetic field? It is the ratio of the volume to the total potential energy. It is the product of the total potential energy and the volume. It is the ratio of the total potential energy to the volume.
It is the ratio of the total potential energy to the volume.
If a closed loop lies partially inside and partially outside a region of changing magnetic field, which is true about the induced electric field along the path? It is zero at points on the path outside the region of changing magnetic field. It is zero at points on the path inside the region of changing magnetic field. It is zero at all points on the path. It is zero at no points on the path.
It is zero at no points on the path.
The current though an inductor is constant. Which is true about the self-induced emf of the inductor? It is in the direction of the current so as to decrease the current. It is in the direction opposite that of the current so as to decrease the current. It is in the direction of the current so as to aid the increase the current. It is in the direction opposite that of the current so as to increase the current. It is zero.
It is zero.
When the charge in the capacitor is maximum, which is true about the current in the inductor? It is maximum. It is half maximum. It is one-fourth maximum. It is zero.
It is zero.
When the electric field magnitude in the capacitor is maximum, which is true about the magnetic field magnitude in the inductor? It is maximum. It is half maximum. It is one-fourth maximum. It is zero.
It is zero.
When the magnetic field magnitude in the inductor is maximum, which is true about the electric field magnitude in the capacitor? It is zero. It is maximum. It is half maximum. It is one-fourth maximum.
It is zero.
When the magnetic flux through a loop increases, which is true about the induced current? It produces a magnetic field in the direction opposite the existing magnetic field. It produces a magnetic field but the direction depends on the rate at which the existing field changes. It produces a magnetic field in the same direction as the existing magnetic field.
It produces a magnetic field in the direction opposite the existing magnetic field.
When the magnetic flux through a loop decreases, which is true about the induced current? It produces a magnetic field but the direction depends on the rate at which the existing field changes. It produces a magnetic field in the same direction as the existing magnetic field. It produces a magnetic field in the direction opposite the existing magnetic field.
It produces a magnetic field in the same direction as the existing magnetic field.
When the magnetic flux through a loop changes, which is always true about the induced current? It produces a magnetic field that opposes the existing magnetic field. It produces a magnetic field that is in the same direction as the existing magnetic field. It produces a magnetic field that opposes the change in the existing magnetic field. It produces a magnetic field that enhances the change in the existing magnetic field.
It produces a magnetic field that opposes the change in the existing magnetic field.
If you double the current through an inductor, what happens to the inductance of the inductor? It is halved. It remains the same. It is doubled.
It remains the same.
Which is true about the inductance of an inductor? Its value depends on the amount of the magnetic flux linkage. Its value does not depend on the amount of the magnetic flux linkage. Its value depends inversely on the amount of the magnetic flux linkage.
Its value does not depend on the amount of the magnetic flux linkage.
Which is true about the inductance of an inductor? Its value does not depend on the current through the inductor. Its value depends on the current through the inductor. Its value depends inversely on the current through the inductor.
Its value does not depend on the current through the inductor.
Which describes the magnetic field of long straight wire that carries current uniformly across its circular cross-sectional area? The field is uniform (but nonzero) throughout the interior of the wire and is progressively smaller as you move outward away from the surface. The field is zero at the surface and progressively larger as you move away from the surface, either toward the center or away from the center. The field is zero at the surface and within the wire and it is progressively larger as you move outward away from the surface. The field is zero throughout the interior of the wire and is progressively larger as you move outward away from the surface. The field is maximum at the surface and progressively smaller as you move away from the surface, either toward the center or away from the center.
The field is maximum at the surface and progressively smaller as you move away from the surface, either toward the center or away from the center.
We set up two parallel currents in opposite directions. Which describes the magnetic field set up by current 1 at a point on current 2? The field is in the direction opposite current 2. The field is perpendicular to current 2. The field is in the same direction as current 2.
The field is perpendicular to current 2.
We set up two parallel currents in the same direction. Which describes the magnetic field set up by current 1 at a point on current 2? The field is in the same direction as current 2. The field is in the direction opposite current 2. The field is perpendicular to current 2.
The field is perpendicular to current 2.
Which describes the magnetic field at the center of curvature of a circular arc of current? The field does not depend on the angle subtended by the arc. The field is inversely proportional to the angle subtended by the arc. The field is proportional to the angle subtended by the arc.
The field is proportional to the angle subtended by the arc.
Which describes the magnetic field at a point inside a long wire that carries current uniformly across its circular cross-sectional area? The field is directed radially outward. The field is directed radially inward. The field is tangent to a circle through the point and concentric with the wire.
The field is tangent to a circle through the point and concentric with the wire.
Which describes the right-hand rule given in this section? The thumb gives the direction of integration. The fingers give the direction of a positive current through an Amperian loop. The thumb gives the direction of integration. The fingers give the direction of a negative current through an Amperian loop. The fingers give the direction of integration. The thumb gives the direction of a negative current through an Amperian loop. The fingers give the direction of integration. The thumb gives the direction of a positive current through an Amperian loop.
The fingers give the direction of integration. The thumb gives the direction of a positive current through an Amperian loop.
Which describes the flux of a magnetic field that is tangent to a section on a closed surface? The flux is zero. The flux is positive. The flux is negative.
The flux is zero.
We set up two parallel currents in opposite directions. Which describes the magnetic force on each wire due to the other wire? The force on each current is perpendicular to the current and toward the other current. The force on each current is in the opposite the direction of the current. The force on each current is perpendicular to the current and away from the other current. The force on each current is in the direction of the current.
The force on each current is perpendicular to the current and away from the other current.
We set up two parallel currents in the same direction. Which describes the magnetic force on each wire due to the other wire? The force on each current is perpendicular to the current and toward the other current. The force on each current is perpendicular to the current and away from the other current. The force on each current is in the direction opposite that of the current. The force on each current is in the direction of the current.
The force on each current is perpendicular to the current and toward the other current.
In the two-coil setup in this section, if the current in coil 1 is decreasing at a constant rate, which is true? The induced emf in coil 2 is increasing. The induced emf in coil 2 is constant. The induced emf in coil 2 is decreasing.
The induced emf in coil 2 is constant.
In the two-coil setup in this section, if the current in coil 1 is increasing at a constant rate, which is true? The induced emf in coil 2 is increasing. The induced emf in coil 2 is constant. The induced emf in coil 2 is decreasing.
The induced emf in coil 2 is constant.
In the two-coil setup in this section, which is true? The induced emf in each coil depends on how much current is in that coil. The induced emf in each coil depends on how much current is in the other coil. The induced emf in each coil depends on the rate that the current is changing in that coil. The induced emf in each coil depends on the rate that the current is changing in the other coil.
The induced emf in each coil depends on the rate that the current is changing in the other coil.
In using Ampere's law for a solenoid as in this section, which is true about the values of the integration parts? The integrations parallel to the length of the solenoid give a zero result; those perpendicular to the length give a nonzero result. The integrations parallel to the length of the solenoid give a nonzero result; those perpendicular to the length give a zero result. The integrations parallel and perpendicular to the length of the solenoid give a zero result. The integrations parallel and perpendicular to the length of the solenoid give a nonzero result.
The integrations parallel to the length of the solenoid give a nonzero result; those perpendicular to the length give a zero result.
Which is true about a solenoid? The internal magnetic field is weak. The external magnetic field is approximately uniform. The magnetic field is approximately uniform both inside and outside the solenoid. The internal magnetic field is approximately uniform. The external magnetic field is weak.
The internal magnetic field is approximately uniform. The external magnetic field is weak.
In the discussion about pulling the loop from the magnetic field, which is true? The work you do goes into the acceleration of the loop. The work you do goes into thermal energy of the wire. The work done by the magnetic field goes into the acceleration of the loop. The work done by the magnetic field is transferred to you. The work you do goes into the magnetic field.
The work you do goes into thermal energy of the wire.
Which describes the vector calculation of the Biot-Savart law? The length element in the direction of the current is crossed into a vector directed from that element toward the point of measurement. The length element in the direction of the current is dotted into a vector directed from that element toward the point of measurement. The magnetic field vector is crossed into a vector directed from a current-length element toward the point of measurement. The magnetic field vector is dotted into a vector directed from a current-length element toward the point of measurement. The magnetic field vector is crossed into a length element in the direction of the current. The magnetic field vector is dotted into a length element in the direction of the current.
The length element in the direction of the current is crossed into a vector directed from that element toward the point of measurement.
Which describes the magnitude of the magnetic field vectors near a long straight wire carrying current? The magnitudes increase as the distance from the wire increases. The magnitudes are uniform. The magnitudes decrease as the distance from the wire increases.
The magnitudes decrease as the distance from the wire increases.
In the discussion about pulling the loop from the magnetic field, what causes the current in the loop? The motion creates a magnetic field along the loop. The motion increases the magnetic flux through the loop, which induces a current. The motion dissipates energy as thermal energy, which induces a current. The motion decreases the magnetic flux through the loop, which induces a current.
The motion decreases the magnetic flux through the loop, which induces a current.
In the two-coil setup in this section, coil 1 is larger in both the number of turns and the area of each turn. Which is true? The mutual inductance M12 is less than the mutual inductance M21. The mutual inductance M12 is equal to the mutual inductance M21. The mutual inductance M12 is greater than the mutual inductance M21.
The mutual inductance M12 is equal to the mutual inductance M21.
When an RL circuit is connected to a battery, what happens to the potential difference across the resistor and the emf across the inductor? The resistor potential is constant and the inductor emf increases. The resistor potential is constant and the inductor emf decreases. The resistor potential is constant and the inductor emf is constant. The resistor potential decreases and the inductor emf is constant. The resistor potential decreases and the inductor emf increases. The resistor potential decreases and the inductor emf decreases. The resistor potential increases and the inductor emf increases. The resistor potential increases and the inductor emf is constant. The resistor potential increases and the inductor emf decreases.
The resistor potential increases and the inductor emf decreases.
In the demonstration where a magnetic north pole is brought near a loop, which is true about the induced current if we use the same speed but switch to the south end of the magnet? It is smaller and in the same direction as before. It is larger and in the same direction as before. The size and the direction are the same. It is now smaller and in the opposite direction. It is now larger and in the opposite direction. The size is the same but the current is now reversed.
The size is the same but the current is now reversed.
Which describes the spacing of the magnetic field lines near a long straight wire carrying current? The spacing increases as the distance from the wire increases. The spacing decreases as the distance from the wire increases. The spacing is uniform.
The spacing increases as the distance from the wire increases
Which describes the right-hand rule given in this section? The thumb gives the direction of the magnetic field and the fingers give the direction of a position vector. The thumb gives the direction of a position vector and the fingers give the direction of the magnetic field. The thumb gives the direction of the magnetic field and the fingers give the direction of the current. The thumb gives the direction of the current and the fingers give the direction of the magnetic field.
The thumb gives the direction of the current and the fingers give the direction of the magnetic field
In applying the right-hand rule as discussed in this section, which is true? The fingers give the direction of the magnetic moment vector; the thumb gives the direction of the current in the current loop. The fingers give the direction of the magnetic field lines; the thumb gives the direction of the current in the current loop. The thumb gives the direction of the magnetic moment vector; the fingers give the direction of the current in the current
The thumb gives the direction of the magnetic moment vector; the fingers give the direction of the current in the current
If we decrease the inductance in an RL circuit, what happens to the time required for the current to reach, say, 50% of its final value after the battery is connected? The time is increased. The time is decreased. The time is the same.
The time is decreased.
If we increase the resistance in an RL circuit, what happens to the time required for the current to reach, say, 50% of its final value after the battery is connected? The time is decreased. The time is the same. The time is increased.
The time is decreased.
If we decrease the resistance in an RL circuit, what happens to the time required for the current to reach, say, 50% of its final value after the battery is connected? The time is decreased. The time is the same. The time is increased.
The time is increased.
If we increase the inductance in an RL circuit, what happens to the time required for the current to reach, say, 50% of its final value after the battery is connected? The time is decreased. The time is the same. The time is increased.
The time is increased.
Which is true about the exponential expressions in this section? The value of 1- exp(-t/τ ) increases with time and the value of exp(-t/τ ) decreases with time. The value of 1- exp(-t/τ ) decreases with time and the value of exp(-t/τ ) increases with time.
The value of 1- exp(-t/τ ) increases with time and the value of exp(-t/τ ) decreases with time.
If two parallel currents repel each other, which describes the directions of the currents? They are in the same direction. They are in opposite directions. They can be in either the same direction or in opposite directions, depending on the relative sizes of the currents.
They are in opposite directions.
In Ampere's law, which describes the integrand? We take a cross product of the magnetic field and a length element along the path to get the component of the field that is parallel to the element. We take a cross product of the magnetic field and a length element along the path to get the component of the field that is perpendicular to the element. We take a dot product of the magnetic field and a length element along the path to get the component of the field that is perpendicular to the element. We take a dot product of the magnetic field and a length element along the path to get the component of the field that is parallel to the element.
We take a dot product of the magnetic field and a length element along the path to get the component of the field that is parallel to the element.
If a closed loop lies partially inside and partially outside a region of changing magnetic field, which is true about calculating the induced electric field along the path? We use only the area within the flux change to calculate the electric field. We use the full area of the loop to calculate the electric field. The electric field is zero at points along the path that are outside the region of changing magnetic field. The electric field is zero at points within the region of changing magnetic field.
We use only the area within the flux change to calculate the electric field.
When is the magnetic flux on a section of a closed surface equal to zero? When the magnetic field is in the direction opposite that of the section's area vector. When the magnetic field is perpendicular to the section's area vector. When the magnetic field is in the direction of the section's area vector.
When the magnetic field is perpendicular to the section's area vector.
In this section we derived a formula for finding the magnetic field set up by the current in a wire that forms a circular arc. Where is the equation valid? anywhere internal to the arc anywhere outside the arc any point on the wire itself at the center of curvature of the arc
at the center of curvature of the arc
