physics final
An electron moving in the direction of the +x-axis enters a magnetic field. If the electron experiences a magnetic deflection in the -y direction, the direction of the magnetic field in this region points in the direction of the
-z-axis
An electron moving in the direction of the +x-axis enters a magnetic field. If the electron experiences a magnetic deflection in the -y direction, the direction of the magnetic field in this region points in the direction of the
-z-axis.
In the figure, a conducting rod is shown moving to the right along U-shaped conducting rails. The apparatus is in a uniform magnetic field perpendicular to the plane of the figure. As viewed from above, in what direction does the induced current flow in the U-shaped apparatus?
An induced current flows counterclockwise in the U-shaped apparatus. magnetic flux is increasing so the because of the induced field the current would flow counterclockwise.
A circular loop of wire lies flat on a level table top in a region where the magnetic field vector points straight upward. The magnetic field suddenly vanishes. As viewed from above, in what direction does the induced current flow in the loop of wire?
An induced current flows counterclockwise in the loop of wire.
what is true about inductors?
An inductor always resists any change in the current through it.
A positive point charge Q is fixed on a very large horizontal frictionless tabletop. A second positive point charge q is released from rest near the stationary charge and is free to move. Which statement best describes the motion of q after it is released?
As it moves farther and farther from Q, its speed will keep increasing.
A disk with a radius of R is oriented with its normal unit vector at an angle Θ with respect to a uniform electric field. Which of the following represent the electric flux through the disk?
E(πR^2)sinϕ E(πR^2)cosΘ know that general equation is E*A*cos(theta) theta is the angle between area vector and electric field
A point charge Q is located a short distance from a point charge 3Q, and no other charges are present. If the electrical force on Q is F, what is the electrical force on 3Q?
F
What is true about Gauss's Law
If a Gaussian surface is completely inside an electrostatic conductor, the electric field must always be zero at all points on that surface. The electric flux passing through a Gaussian surface depends only on the amount of charge inside that surface, not on its size or shape
What is true about electric fields?
In a uniform electric field, the field lines are straight, parallel, and uniformly spaced. Electric field lines near positive point charges radiate outward. The electric force acting on a point charge is proportional to the magnitude of the point charge.
What is true about electromagnetic induction?
It is possible to induce a current in a closed loop of wire by change the orientation of a magnetic field enclosed by the wire. It is possible to induce a current in a closed loop of wire by changing the strength of a magnetic field enclosed by the wire. It is possible to induce a current in a closed loop of wire located in a uniform magnetic field by either increasing or decreasing the area enclosed by the loop. It is possible to induce a current in a closed loop of wire without the aid of a power supply or battery.
What is true about an electron moving in the direction of an electric field?
Its kinetic energy decreases as it moves in the direction of the electric field. Its potential energy increases as its kinetic energy decreases. Its electric potential energy increases as it goes from high to low potential
What is true about kirchoff's rule?
Kirchhoff's junction rule is based on the conservation of energy. Kirchhoff's loop rule is based on the conservation of charge. The sum of the changes in potential around any closed loop of a circuit must equal zero At any junction point in a circuit, the sum of all the currents entering the junction must equal the sum of all the currents leaving the junction.
A circular loop of wire lies flat on a level table top. A bar magnet is held stationary above the circular loop with its north pole point downward. As viewed from above, in what direction does the induced current flow in the loop of wire?
No current is induced in the loop of wire
A positive charge is moved from point A to point B along an equipotential surface. How much work is performed or required in moving the charge?
No work is performed or required in moving the positive charge from point A to point B. Because it is an equipotential surface, it means the potential is the same everywhere so when looking at the change in potential, it will be zero
Ions having equal charges but masses of M and 2M are accelerated through the same potential difference and then enter a uniform magnetic field perpendicular to their path. If the heavier ions follow a circular arc of radius R, what is the radius of the arc followed by the lighter?
R/√2 Fc=Fb (mv^2)/r=qvB
Two charged objects are separated by some distance. The charge on the first object is greater than the charge on the second object. How does the force between the two objects compare?
The charged objects exert electrostatic forces on each other that are equal in magnitude and opposite in direction.
A charged particle enters into a uniform magnetic field such that its velocity vector is perpendicular to the magnetic field vector. Ignoring the particle's weight, what type of path will the particle follow?
The charged particle will follow a circular path.
When an LRC series circuit is at resonance, which one of the following statements about that circuit is accurate?
The current amplitude is a maximum
When an LRC series circuit is at resonance, which one of the following statements about that circuit is accurate?
The current amplitude is a maximum.
A bar magnet is held vertically with its upper end a little bit below the center of a horizontal metal ring. The upper end of the magnet is its north pole, as shown in the figure. The bar magnet is now dropped. An observer views the ring from above its center. To this observer, how will the induced current in the ring behave as the magnet falls?
The current will flow counter-clockwise and be decreasing.
A magnetic force is acting on a electric charge in a uniform magnetic field, what is true about it.
The direction of the magnetic force acting on a moving charge in a magnetic field is perpendicular to the direction of the magnetic field. A magnetic force is exerted on an electric charge moving through a uniform magnetic field. An electric charge moving perpendicular to a magnetic field experiences a magnetic force. The direction of the magnetic force acting on a moving electric charge in a magnetic field is perpendicular to the direction of motion.
Two long parallel wires are placed side by side on a horizontal table. The wires carry equal currents in the same direction. Which of the following statements are true?
The magnetic force between the two wires is attractive. The magnetic field is a maximum at a point midway between the two wires
When a point charge of +q is placed on one corner of a square, an electric field strength of 2 N/C is observed at the center of the square. Suppose three identical charges of +q are placed on the remaining three corners of the square. What is the magnitude of the net electric field at the center of the square?
The magnitude of the net electric field at the center of the square is 0 N/C.
Two very long parallel wires are a distance d apart and carry equal currents in opposite directions. The locations where the net magnetic field due to these currents is equal to zero are
The net field is not zero anywhere.
An uncharged conductor has a hollow cavity inside of it. Within this cavity there is a charge of +10µC that does not touch the conductor. There are no other charges in the vicinity. What is true about this conductor?
The outer surface of the conductor contains +10µC of charge and the inner surface contains -10µC.
A conducting sphere contains positive charge distributed uniformly over its surface, what is true about it?
The potential at the center of the sphere is the same as the potential at the surface.
An inductor is connected in series to a fully charged capacitor. What is true about it?
The stored electric field energy can be greater than the stored magnetic field energy. As the capacitor is discharging, the current is increasing. The stored electric field energy can be equal to the stored magnetic field energy. The stored electric field energy can be less than the stored magnetic field energy.
A resistor, an inductor, and a capacitor are connected in series to an AC source. The AC source is operating at the resonance frequency. What is true about it? 1. The total voltage across the inductor and the capacitor at any instant is equal to zero. 2. The peak voltage across the resistor is equal to the peak voltage across the capacitor. 3. The current is in phase with the driving voltage. 4. The peak voltage across the inductor is greater than the peak voltage across the capacitor. 5. The peak voltage across the resistor is equal to the peak voltage across the inductor. 6. The peak voltage across the capacitor is greater than the peak voltage across the inductor.
The total voltage across the inductor and the capacitor at any instant is equal to zero. The current is in phase with the driving voltage.
If the resistance in a circuit connected to a constant current is halved, how is the voltage in the circuit affected?
The voltage is reduced by a factor of 2.
A capacitor is charging in a simple RC circuit with a dc battery. Which one of the following statements about this capacitor is accurate?
There is a magnetic field between the capacitor plates, even though no charge travels between them, because the electric flux between the plates is changing.
A solid conducting sphere is placed in an external uniform electric field. With regard to the electric field on the sphere's interior, which statement is correct? A solid conducting sphere is placed in an external uniform electric field. With regard to the electric field on the sphere's interior, which statement is correct?
There is no electric field on the interior of the conducting sphere.
Is it possible for the electric field between two positive charges to equal zero along the line joining the two charges?
Yes, regardless of the magnitude of the two charges.
An ac source of period T and voltage amplitude Vmax is connected to a single unknown ideal element that is either a resistor, an inductor, or a capacitor. At time t = 0 the voltage is zero. At time t = T/4 the current in the unknown element is equal to zero and the voltage is V = + Vmax. At time t = T/2 the current is I = −Imax , where Imax is the current amplitude. What is the unknown element?
a capacitor initially the capacitor is uncharged, because at t=0, the voltage is 0, when current is at max that is when the capacitor is fully charged correlating to where it was stated that when current was max, the voltage was also max
In the figure, two parallel wires carry currents of magnitude I in opposite directions. A rectangular loop is midway between the wires. The current I is decreasing with time. The induced current through the resistor R is
b to a the magnetic fields from the wireswires are going in opposite directions so the magnetic field is decreasing so the induced current would go in a direction to oppose that
A circular loop of wire lies in the plane of the paper. An increasing magnetic field points out of the paper. What is the direction of the induced current in the loop?
clockwise
An electron is initially moving to the right when it enters a uniform electric field directed upwards. What is its trajectory?
downwards in a parabolic motion
An electron is traveling horizontally toward the north in a uniform magnetic field that is directed vertically downward. In what direction does the magnetic force act on the electron?
east
A resistor and a capacitor are connected in series across an ideal battery having a constant voltage across its terminals. At the moment contact is made with the battery the voltage across the resistor is
equal to the battery's terminal voltage.
true or false, if the electric flux through a closed surface is zero, the electric field at points on that surface must be zero.
false
Under electrostatic conditions, the electric field just outside the surface of any charged conductor
is always perpendicular to the surface of the conductor.
The long straight wire in the figure carries a current I that is decreasing with time at a constant rate. The circular loops A, B, and C all lie in a plane containing the wire. The induced emf in each of the loops A, B, and C is such that (loop A is above the wire, loop B is on the wire, and loop C is below the wire)
loop A has a counter-clockwise emf, loop B has no induced emf, and loop C has a clockwise emf. to find the direction of the induced emf, find the direction the wire induces a magnetic field on the loops
When electric current is flowing in a metal, the electrons are moving
none of these speeds at the speed of sound in the metal. at the speed of light. at the speed of sound in air. at nearly the speed of light.
A vertical wire carries a current straight down. To the east of this wire, the magnetic field points.
toward the south (imagine that towards you is south)
A negatively charged particle is moving to the right, directly above a wire having a current flowing to the right, as shown in the figure. In which direction is the magnetic force exerted on the particle?
upward do the cross product between the induced magnetic field from the wire and the velocity of the particle
A resistor and a capacitor are connected in series across an ideal battery having a constant voltage across its terminals. At the moment contact is made with the battery the voltage across the capacitor is
zero
