Test bank chapter 20- Magnetism

A charged particle is observed traveling in a circular path in a uniform magnetic field. If the particle had been traveling twice as fast, the radius of the circular path would be A) twice the original radius. B) four times the original radius. C) one-half the original radius. D) one-fourth the original radius.

A

A long straight 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 force on the proton? A) north B) south C) up D) down

A

An electron has an initial velocity to the south but is observed to curve upward as the result of a magnetic field. The direction of the magnetic field is A) to the west. B) to the east. C) upward. D) downward.

A

If the south pole of one bar magnet is brought near the north pole of a second bar magnet, the two magnets will A) attract. B) repel.

A

The force on a current-carrying wire in a magnetic field is equal to zero when A) the current is parallel to the field lines. B) the current is at a 30 degree angle with respect to the field lines. C) the current is at a 60 degree with respect to the field lines. D) the current is perpendicular to the field lines.

A

The south pole of a magnet points toward the Earth's A) South Pole. B) North Pole. C) center. D) middle latitudes

A

Two long parallel wires carry equal currents. The magnitude of the force between the wires is F. The current in each wire is now doubled. What is the magnitude of the new force between the two wires? A) 4F B) 2F C) F/4 D) F/2

A

The magnetic field produced by a long straight current-carrying wire is A) proportional to both the current in the wire and the distance from the wire B) proportional to the current in the wire and inversely proportional to the distance from the wire. C) inversely proportional to the current in the wire and proportional to the distance from the wire. D) inversely proportional to both the current in the wire and the distance from the wire.

B

Two long parallel wires placed side-by-side on a horizontal table carry identical size currents in opposite directions. The wire on your right carries current toward you, and the wire on your left carries current away from you. From your point of view, the magnetic field at the point exactly midway between the two wires A) points up. B) points down. C) points toward you. D) is zero.

B

At double the distance from a long current-carrying wire, the strength of the magnetic field produced by that wire decreases to A) 1/8 of its original value. B) 1/4 of its original value. C) 1/2 of its original value. D) none of the given answers

C

A current carrying loop of wire lies flat on a table top. When viewed from above, the current moves around the loop in a counterclockwise sense. What is the direction of the magnetic field caused by this current, outside the loop? The magnetic field A) circles the loop in a clockwise direction. B) circles the loop in a counterclockwise direction. C) points straight up. D) points straight down.

D

A vertical wire carries a current straight up in a region where the magnetic field vector points due north. What is the direction of the resulting force on this current? A) down B) north C) east D) west

D

Consider two current-carrying circular loops. Both are made from one strand of wire and both carry the same current, but one has twice the radius of the other. Compared to the magnetic field at the center of the smaller loop, the magnetic field at the center of the larger loop is A) 8 times stronger. B) 4 times stronger. C) 2 times stronger. D) none of the given answers

D

The force on a current-carrying wire in a magnetic field is the strongest when A) the current is parallel to the field lines. B) the current is at a 30 degree angle with respect to the field lines. C) the current is at a 60 degree with respect to the field lines. D) the current is perpendicular to the field lines.

D

Two long parallel wires are placed side-by-side on a horizontal table. If the wires carry current in opposite directions, A) one wire is lifted slightly as the other is forced against the table's surface. B) both wires are lifted slightly. C) the wires attract each other. D) the wires repel each other.

D

Two long parallel wires placed side-by-side on a horizontal table carry identical current straight toward you. From your point of view, the magnetic field at the point exactly between the two wires A) points up. B) points down. C) points toward you. D) is zero.

D

When placed askew in a magnetic field, a current carrying loop that is free to rotate in any direction will experience a torque until its magnetic moment vector A) is at right angles to the magnetic field vector. B) makes a 45 degree angle with the magnetic field vector. C) makes an angle of 270 degree with the magnetic field vector. D) is aligned with the magnetic field vector.

D

A charged particle moves across a constant magnetic field. The magnetic force on this particle A) changes the particle's speed. B) causes the particle to accelerate. C) is in the direction of the particle's motion. D) changes the particle's speed causing the particle to accelerate.

B

An electron moving along the +x axis enters a region where there is a uniform magnetic field in the +y direction. What is the direction of the magnetic force on the electron? (+x to right, +y up, and +z out of the page.) A) +z direction B) -z direction C) -y direction D) -x direction

B

If a bar magnet is divided into two equal pieces, A) the north and south poles are separated. B) two magnets result. C) the magnet properties are destroyed. D) an electric field is created.

B

If the north poles of two bar magnets are brought close to each other, the magnets will A) attract. B) repel.

B

The Earth's geographic North Pole is magnetically a A) north pole. B) south pole.

B

The maximum torque on a current carrying loop occurs when the angle between the loop's magnetic moment and the magnetic field vector is A) 0 degrees B) 90 degrees C) 180 degrees D) none of the given answers

B

A charged particle moves with a constant speed through a region where a uniform magnetic field is present. If the magnetic field points straight upward, the magnetic force acting on this particle will be maximum when the particle moves A) straight upward. B) straight downward. C) in a plane parallel to the Earth's surface. D) upward at an angle of 45e above the horizontal

C

A current carrying circular loop of wire lies flat on a table top. When viewed from above, the current moves around the loop in a counterclockwise sense. What is the direction of the magnetic field caused by this current, inside the loop? The magnetic field A) circles the loop in a clockwise direction. B) circles the loop in a counterclockwise direction. C) points straight up. D) points straight down

C

A particle carrying a charge of +e travels in a circular path in a uniform magnetic field. If instead the particle carried a charge of +2e, the radius of the circular path would have been A) twice the original radius. B) four times the original radius. C) one-half the original radius. D) one-fourth the original radius.

C

An electric current produces A) a gravitational field. B) an electric field. C) a magnetic field. D) an electromagnetic field

C

At a particular instant, an electron moves eastward at speed V in a uniform magnetic field that is directed straight downward. The magnetic force that acts on it is A) zero. B) directed upward. C) directed to the south. D) directed to the north

C

The SI unit of magnetic field is the A) weber. B) gauss. C) tesla. D) lorentz.

C

The direction of the force on a current-carrying wire in a magnetic field is described by which of the following? A) perpendicular to the current only B) perpendicular to the magnetic field only C) perpendicular to both the current and the magnetic field D) perpendicular to neither the current or the magnetic field

C

Two long parallel wires are placed side-by-side on a horizontal table. If the wires carry current in the same direction, A) one wire is lifted slightly as the other wire is forced against the table's surface. B) both wires are lifted slightly. C) the wires attract each other. D) the wires repel each other.

C

Which of the following is correct? A) When a current carrying wire is in your right hand, thumb in the direction of the magnetic field lines, your fingers point in the direction of the current. B) When a current carrying wire is in your left hand, thumb in the direction of the magnetic field lines, your fingers point in the direction of the current. C) When a current carrying wire is in your right hand, thumb in the direction of the current, your fingers point in the direction of the magnetic field lines. D) When a current carrying wire is in your left hand, thumb in the direction of the current, your fingers point in the direction of the magnetic field lines.

C

vertical wire carries a current straight down. To the east of this wire, the magnetic field points A) north. B) east. C) south. D) down

C

1 T is equivalent to A) 1 N*m/A. B) 1 N*A/m. C) V*m/A. D) N/A*m

D

A charged particle is injected into a uniform magnetic field such that its velocity vector is perpendicular to the magnetic field vector. Ignoring the particle's weight, the particle will A) move in a straight line. B) follow a spiral path. C) move along a parabolic path. D) follow a circular path.

D

A charged particle moves and experiences no magnetic force. From this, we can conclude that A) no magnetic field exists in that region of space. B) the particle is moving parallel to the magnetic field. C) the particle is moving at right angles to the magnetic field. D) either no magnetic field exists or the particle is moving parallel to the field.

D

A horizontal wire carries a current straight toward you. From your point of view, the magnetic field caused by this current A) points directly away from you. B) points to the left. C) circles the wire in a clockwise direction. D) circles the wire in a counter-clockwise direction.

D

A wire lying in the plane of the page carries a current toward the bottom of the page. What is the direction of the magnetic force it produces on an electron that is moving perpendicularly toward the wire, also in the plane of the page, from your right? A) zero B) perpendicular to the page and towards you C) perpendicular to the page and away from you D) toward the top of the page E) toward the bottom of the page

E