FINAL EXAM CONCEPT REVIEW

clockwise

A bar magnet is oriented above a copper ring, as shown in the figure. If the magnet is kept fixed while the ring is dropped, what is the direction of the current induced in the ring, as viewed from below the ring? The figure shows a bar magnet placed above a ring. The ring is located in a horizontal plane. Poles of the magnet and the center of the ring lie on the same vertical line. North pole of the magnet is above its south pole.

three times a large as before.

A capacitor C is connected in series with a resistor R across a battery and an open switch. If a second capacitor of capacitance 2C is connected in parallel with the first one, the time constant of the new RC circuit will be

2R.

A charged particle is observed traveling in a circular path of radius R in a uniform magnetic field. If the particle was traveling twice as fast, the radius of the circular path would be

clockwise

A circular coil of copper wire is lying flat on a horizontal table. A bar magnet is held above the center of the coil with its south pole downward. The magnet is released from rest and falls toward the coil. As viewed from above, what is the direction of the current induced in the coil as the magnet approaches the coil?

clockwise

A coil lies flat on a horizontal tabletop in a region where the magnetic field points straight down. The magnetic field disappears suddenly. When viewed from above, what is the direction of the induced current in this coil as the field disappears?

The induced current flows counterclockwise.

A coil lies flat on a tabletop in a region where the magnetic field vector points straight up. The magnetic field vanishes suddenly. When viewed from above, what is the sense of the induced current in this coil as the field fades?

4ε

A coil of wire containing N turns is in an external magnetic field that is perpendicular to the plane of the coil and it steadily changing. Under these circumstances, an emf ε is induced in the coil. If the rate of change of the magnetic field and the number of turns in the coil are now doubled (but nothing else changes), what will be the induced emf in the coil?

with the north pole pointing in the direction of the magnetic field

A compass in a magnetic field will line up __________.

counterclockwise in the east coil and clockwise in the west coil.

A long straight wire lies on a horizontal table and carries an ever-increasing current toward the north. Two coils of wire lie flat on the table, one on either side of the wire. When viewed from above, the direction of the induced current in these coils is

toward the north

A long, straight, horizontal wire carries current toward the east. A proton moves toward the east alongside and just south of the wire. What is the direction of the magnetic force on the proton?

R/2

A particle carrying a charge of +e travels in a circular path of radius R in a uniform magnetic field. If instead the particle carried a charge of +2e, the radius of the circular path would have been

A converging lens or concave mirror.

A real image of an object can be formed by

A converging lens.

A real image of an object can be formed by

The potentials at points A and B are equal, and the potential at point C is lower than the potential at point A.

A region of space contains a uniform electric field, directed toward the right, as shown in the figure. Which statement about this situation is correct?

trajectory Z

An electron is initially moving to the right when it enters a uniform electric field directed upwards, as shown in the figure. Which trajectory (X, Y, Z, or W) will the electron follow in the field? The figure shows an electron with an initial velocity v, directed horizontally to the right, entering a uniform electric field E directed upwards. Four trajectories of the electron, labeled X, Y, Z, and W, are shown. Trajectory X goes upward along the field. Trajectory Y smoothly deviates from horizontal upward, forming a convex curve. Trajectory Z smoothly deviates from the horizontal downward, forming a concave curve. Trajectory W goes horizontally to the right.

4C

An ideal parallel-plate capacitor has a capacitance of C. If the area of the plates is doubled and the distance between the plates is halved, what is the new capacitance?

counterclockwise

An outer metal ring surrounds an inner metal ring, as shown in the figure. The current in the outer ring is counterclockwise and decreasing. What is the direction of the induced current in the inner ring? The figure shows two concentric rings. The current in the outer ring is directed counterclockwise.

both its electrical potential and electric potential energy remain constant.

As a proton moves in a direction perpendicular to the electric field lines

it is moving from high potential to low potential and losing electric potential energy.

As a proton moves in the direction the electric field lines

it is moving from high potential to low potential and gaining electric potential energy.

As an electron moves in the direction the electric field lines

Double the plate separation. Halve the plate area.

Consider a charged parallel-plate capacitor. How can its capacitance be halved?

Halve the plate separation and double the plate area.

Consider a charged parallel-plate capacitor. Which combination of changes would quadruple its capacitance?

θ2<θ1

Consider a ray of light that propagates from water (n=1.33) to glass (n=1.52). If the incident ray strikes the water-glass interface at an angle θ1≠0, which of the following relations regarding the angle of refraction θ2 is correct?

Decrease the spacing between the plates of the capacitor.

Consider an air-filled charged capacitor. How can its capacitance be increased?

The resistance of wire #1 is twice as high as that of wire #2.

Copper wire #1 has a length L and a radius b. Copper wire #2 has a length 2L and a radius 2b. Which statement about the resistance across the ends of the wires is true?

the force between two point charges.

Coulomb's law describes __________

quadruple.

Doubling the potential across a given capacitor causes the energy stored in that capacitor to

positive.

Focal length (f) of a converging and concave mirror is

negative.

Focal length (f) of a diverging and convex mirror is

zero

Four charged particles (two having a charge +Q and two having a charge -Q) are arranged in the xy-plane, as shown in the figure. These particles are all equidistant from the origin. The electric potential (relative to infinity) at point P on the z-axis due to these particles, is

The equivalent resistance is less than that of the smallest resistor.

Four unequal resistors are connected in a parallel with each other. Which one of the following statements is correct about this combination?

The equivalent resistance is more than the largest resistance.

Four unequal resistors are connected in series with each other. Which one of the following statements is correct about this combination?

larger, farther from

If s′ gets ______, the distance between the lens and the image gets larger. Since the detector case can't be moved, the only solution is to move the lens ________ the detector.

quadruple in magnitude.

If the current flowing through a circuit of constant resistance is doubled, the power dissipated by that circuit will

decrease to one-half its original value.

If the resistance in a constant voltage circuit is doubled, the power dissipated by that circuit will

at the focal point of the lens

In the way that a magnifier is usually used, the object is placed __________.

The three loops of wire shown in the figure are all hanging in the same uniform magnetic field B⃗ that is perpendicular to the page and does not vary with time. Loop 1 swings back and forth like the bob in a pendulum, Loop 2 rotates about a vertical axis, and Loop 3 oscillates up and down at the end of a spring. Which loop (or loops) will have an emf induced in them?

Loop 2

The wire in the figure carries a current I that is increasing with time at a constant rate. The wire and the three loops are all in the same plane. What is true about the currents induced in each of the three loops shown?

Loop A has clockwise current, loop B has no induced current, and loop C has counterclockwise current.

The wire in the figure carries a current I that is decreasing with time at a constant rate. The wire and the three loops are all in the same plane. What is true about the currents induced in each of the three loops shown?

Loop A has counterclockwise current, loop B has no induced current, and loop C has clockwise current.

θ2>θ1

Now consider a ray of light that propagates from water (n=1.33) to air (n=1). If the incident ray strikes the water-air interface at an angle θ1≠0, which of the following relations regarding the angle of refraction, θ2, is correct?

in parallel across the source.

Suppose you have two capacitors and want to use them to store the maximum amount of energy by connecting them across a voltage source. You should connect them

farther from

The card must be moved ______ the lens to bring the lamp into focus.

both perpendicular to the velocity and perpendicular to the magnetic field

The direction of the magnetic force on a moving charged particle in a magnetic field is __________.

double the charge to 2Q.

The electric field at point P due to a point charge Q a distance R away from P has magnitude E. In order to double the magnitude of the field at P, you could

zero

The electric field inside a metallic conductor is _____.

400 V

The electric potential at a distance of 4 m from a certain point charge is 200 V relative to infinity. What is the potential (relative to infinity) at a distance of 2 m from the same charge?

uniform

The field inside a charged parallel-plate capacitor is __________.

at the same distance behind the mirror as the object is in front of the mirror.

The image formed in a plane mirror is

diverging, farther from

The lamp is closer, so its rays are ______ as they leave _______ the lamp; consequently, they come to focus the lens than the moon's rays do.

It is ½ as large.

The length of a certain wire is doubled and at the same time its radius is also doubled. What is the new resistance of this wire?

It is reduced by a factor of 4.

The length of a certain wire is kept same while its radius is doubled. What is the new resistance of this wire?

It does not change.

The length of a certain wire is kept same while its radius is doubled. What is the new resistivity of this wire?

circles around the wire

The magnetic field lines due to a straight, current-carrying wire are _________

the current is perpendicular to the magnetic field lines.

The magnetic force on a current-carrying wire in a magnetic field is the strongest when

focal length

The moon is so far away we can consider the rays to be parallel, so they come to focus at the distance of the _________ from the lens, that means the card with the moon's image focused on it is this far from the lens.

1/s+1/s′=1/f

The object distance, image distance, and focal length are related by

A circular wire ring is situated above a long straight wire, as shown in the figure. The straight wire has a current I flowing to the right, and this current is increasing at a constant rate. Which of the following statements is true?

There is an induced current in the wire ring, directed in clockwise orientation.

- Converging lens - Concave mirror In both cases below, the object is closer to the lens or mirror than the focal point. - Diverging lens - Convex mirror

These four cases give virtual images that are upright (the magnification m is positive). The image distance s' is negative

- Converging lens - Concave mirror The object is farther from the lens or mirror than the focal point.

These two cases give real images that are inverted (the magnification m is negative). The image distance s' is positive.

Q/3

Three identical capacitors are connected in parallel to a potential source (battery). If a charge of Q flows into this combination, how much charge does each capacitor carry?

Fnew/Fold = 1/4 or 0.25

Two charged particles are separated by 10 cm. Suppose the charge on each particle is quadrupled. By what factor does the electric force between the particles change?

1/4F

Two identical small charged spheres are a certain distance apart, and each one initially experiences an electrostatic force of magnitude F due to the other. With time, charge gradually diminishes on both spheres by leaking off. When each of the spheres has lost half its initial charge, what will be the magnitude of the electrostatic force on each one?

It remains the same.

Two point charges, Q1 and Q2, are separated by a distance R. If the magnitudes of both charges are halved and their separation is also halved, what happens to the electrical force that each charge exerts on the other one?

The force on A is exactly equal to the force on B.

Two tiny beads are 25 cm apart with no other charges or fields present. Bead A carries 10 µC of charge and bead B carries 1 µC. Which one of the following statements is true about the magnitudes of the electric forces on these beads?

larger

We see that if s gets smaller and f doesn't change, the only way the equality will hold is for s′ to get __________

+1

What is the minimum value that the index of refraction can have?

the ability to store charge

What property of objects is best measured by their capacitance?

The lens should form the image at the near point.

When glasses (or contact lenses) are used to correct farsightedness, where should the corrective lens form an image of an object located between the eye and the near point in order for the eye to form a clear image of that object?

The lens should form the image at the far point.

When glasses (or contact lenses) are used to correct nearsightedness, where should the corrective lens form an image of an object located at infinity in order for the eye to form a clear image of that object?

increases.

When light propagates from a material with a given index of refraction into a material with a smaller index of refraction, the speed of the light

The capacitor with the largest capacitance has the most charge. The potential difference across each capacitor is the same.

When two or more different capacitors are connected in parallel across a potential source (battery), which of the following statements must be true? (There could be more than one correct choice.)

Each capacitor carries the same amount of charge. The equivalent capacitance of the combination is less than the capacitance of any of the capacitors. The total voltage across the combination is the algebraic sum of the voltages across the individual capacitors.

When two or more different capacitors are connected in series across a potential source, which of the following statements must be true? (There could be more than one correct choice.)

Arrow A (Electric field points from positive to negative)

Which one of the arrows shown in the figure best represents the direction of the electric field between the two uniformly charged metal plates? The figure shows two horizontal uniformly charged metal plates. The upper plate is charged positively, and the lower plate is charged negatively. Four arrows, labeled A, B, C, and D, are shown. Arrow A points downward. Arrow B points upward. Arrow C points to the right. Arrow D points to the left.

virtual and upright

Which one of the following sets of characteristics describes the image formed by a plane mirror?

3 cm × 5 cm.

You are given a copper bar of dimensions 3 cm × 5 cm × 8 cm and asked to attach leads to it in order to make a resistor. If you want to achieve the largest possible resistance, you should attach the leads to the opposite faces that measure