Physics 2 Chapter 20

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? (Page Ref: Sec. 20.6)

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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.) (Page Ref: Sec. 20.4)

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A wire carries a current of 10 A in a direction of 30° with respect to the direction of a 0.30-T magnetic field. Find the magnitude of the magnetic force on a 0.50-m length of the wire. (Page Ref: Sec. 20.3)

0.75 N

At double the distance from a long current-carrying wire, the strength of the magnetic field produced by that wire decreases to (Page Ref: Sec. 20.5)

1/2 of its original value.

How many turns should a 10-cm long solenoid have if it is to generate a 1.5 × 10-3 T magnetic field on 1.0 A of current? (Page Ref: Sec. 20.7)

119

What is the magnetic moment of a rectangular loop of 120 turns that carries 6.0 A if its dimensions are 4.0 cm × 8.0 cm? (Page Ref: Sec. 20.9-20.10)

2.3 A·m2

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? (Page Ref: Sec. 20.6)

4F

Two long parallel wires carry currents of 20 A and 5.0 A in opposite directions. The wires are separated by 0.20 m. What is the magnetic field midway between the two wires? (Page Ref: Sec. 20.5)

5.0 × 10-5 T

How much current must flow for 1.0 × 10-3 T of magnetic field to be present 1.0 cm from a wire? (Page Ref: Sec. 20.5)

50 A

A circular wire loop of area 0.25 m2 carries a current of 5.0 A. The coil lies in a horizontal plane with the current flowing in the counterclockwise direction when viewed from above. At this point, the Earth's magnetic field is 1.2 × 10-4 T directed 60° below the horizontal. What is the magnitude of the torque which acts on the loop? (Page Ref: Sec. 20.9-20.10)

7.5 × 10-5 m·N

A proton moving at 4.0 × 104 m/s horizontally enters a region where a magnetic field of 0.13 T is present, directed vertically downward. What force acts on the proton? (Page Ref: Sec. 20.4)

8.3 × 10-16 N

The maximum torque on a current carrying loop occurs when the angle between the loop's magnetic moment and the magnetic field vector is

90°

1 T is equivalent to

N/A·m.

A horizontal wire carries a current straight toward you. From your point of view, the magnetic field caused by this current (Page Ref: Sec. 20.2)

circles the wire in a counter-clockwise direction.

At a particular instant, a proton moves eastward at speed V in a uniform magnetic field that is directed straight downward. The magnetic force that acts on it is (Page Ref: Sec. 20.4)

directed to the north.

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 (Page Ref: Sec. 20.4)

in a plane parallel to the Earth's surface.

A mass spectrometer is a device to measure the _______ of atoms.

mass

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 (Page Ref: Sec. 20.5)

points down.

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 (Page Ref: Sec. 20.2)

points straight down.

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 (Page Ref: Sec. 20.4)

to the west.

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? (Page Ref: Sec. 20.6)

toward the bottom of the page

The Earth's magnetic poles do not coincide with the geographic poles.

true

If a bar magnet is divided into two equal pieces,

two magnets result.

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? (Page Ref: Sec. 20.3)

west

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 (Page Ref: Sec. 20.5)

zero