Question 1

An electron enters a uniform magnetic field of 0.0600 T at an angle of 61.4^$\circ$ to the magnetic field lines.The electron will travel in a helical path of radius 4.80 * 10^-5 m.Find the speed of the electron.

A)6.13 * 10⁵ m/s
B)6.00 * 10⁵ m/s
C)5.06 * 10⁵ m/s
D)5.76 * 10⁵ m/s

Accepted Answer

The radius of the helical path $r$ is given by the formula $r = \frac{mv_{\perp}}{qB}$, where $m$ is the mass of the electron, $v_{\perp}$ is the component of the velocity perpendicular to the magnetic field, $q$ is the charge of the electron, and $B$ is the magnetic field strength. Given $r = 4.80 \times 10^{-5} \, \text{m}$ and $B = 0.0600 \, \text{T}$, and knowing the values of $m = 9.11 \times 10^{-31} \, \text{kg}$ and $q = 1.60 \times 10^{-19} \, \text{C}$ for an electron, we can solve for $v_{\perp}$. However, to find the total speed $v$ of the electron, we use the angle $61.4^\circ$ to relate $v_{\perp}$ to $v$ as $v_{\perp} = v \sin(61.4^\circ)$. Substituting the known values and solving for $v$ gives a speed of approximately $5.76 \times 10^6 \, \text{m/s}$.

Question 2

A straight wire of length 3.5 m carries a current of 42 A and it is placed on a horizontal table in a horizontal uniform magnetic field.The wire makes an angle of 44^$\circ$ with the magnetic field lines.If the magnitude of the magnetic force on the wire is 9.0 N,what is the magnitude of the magnetic field?

A)0.021 T
B)0.067 T
C)0.088 T
D)0.14 T
E)0.23 T

Accepted Answer

The magnetic force on a current-carrying wire is given by $F = BIL\sin(\theta)$, where $F$ is the force, $B$ is the magnetic field strength, $I$ is the current, $L$ is the length of the wire, and $\theta$ is the angle between the wire and the magnetic field. Rearranging for $I$, we get $I = \frac{F}{BL\sin(\theta)}$. Substituting the given values: $I = \frac{9.0}{0.14 \times 3.5 \times \sin(44^\circ)}$, calculating this gives approximately 26 A, which corresponds to choice E.

Question 3

The magnetic force experienced by a charged particle always points&#10;A)in the same direction as the magnetic field.&#10;B)in the opposite direction as the magnetic field.&#10;C)Either A or B is correct depending on the charge of the particle experiencing the force.&#10;D)None are correct.&#10;

Accepted Answer

The magnetic force on a charged particle is always perpendicular to both the magnetic field and the velocity of the particle, not in the same or opposite direction as the magnetic field. This is described by the right-hand rule.

Question 4

If immersed in magnetic fields of the same magnitude,what can be said about the cyclotron frequencies of protons and electrons?&#10;A)The cyclotron frequency of the protons is larger.&#10;B)The cyclotron frequency of the protons is smaller.&#10;C)The cyclotron frequencies are equal.&#10;D)One needs to know how fast the particles are moving in order to compare their cyclotron frequencies.&#10;

Accepted Answer

The cyclotron frequency, also known as the gyrofrequency, of a charged particle in a magnetic field is given by the formula $f = \frac{qB}{2\pi m}$, where $q$ is the charge of the particle, $B$ is the magnetic field strength, and $m$ is the mass of the particle. Since protons and electrons have the same magnitude of charge but protons have a much larger mass, the cyclotron frequency of protons is smaller than that of electrons when they are in magnetic fields of the same magnitude.

Question 5

A straight wire of length 3.5 m carries a current of 42 A and it is placed on a horizontal table in a horizontal uniform magnetic field.The wire makes an angle of 44^$\circ$ with the magnetic field lines.If the magnitude of the magnetic force on the wire is 9.0 N,what is the magnitude of the magnetic field?

A)0.021 T
B)0.067 T
C)0.088 T
D)0.14 T
E)0.23 T

Accepted Answer

The magnetic force on a current carrying wire in a uniform magnetic field is given by F = BILsinθ, where B is the magnetic field strength, I is the current, L is the length of the wire and θ is the angle between the wire and the magnetic field lines.

Plugging in the given values, we get:

9.0 N = (0.14 T) x (42 A) x (3.5 m) x sinθ

Solving for sinθ, we get:

sinθ = 9.0 N / (0.14 T x 42 A x 3.5 m)

θ = sin-1 (0.253)

θ ≈ 26°

Therefore, the angle between the wire and the magnetic field lines is approximately 26°. The answer is choice C.

Question 6

Two protons move with uniform circular motion in the presence of uniform magnetic fields.Proton one moves twice as fast as proton two.The magnitude of the magnetic field in which proton one is immersed is twice the magnitude of the magnetic field in which proton two is immersed.The radius of the circle around which proton one moves is r.What is the radius of the circle around which proton two moves?

A)r/2
B)r
C)2r
D)4r

Accepted Answer

The radius of the circular path for a charged particle in a magnetic field is given by $r = \frac{mv}{qB}$, where $m$ is the mass of the particle, $v$ is its velocity, $q$ is its charge, and $B$ is the magnetic field strength. For proton one, moving twice as fast in a field twice as strong, both the velocity and the magnetic field strength in the formula increase by a factor of 2, which cancels out, leaving the radius unchanged. Therefore, the radius for proton two remains $r$.

Question 7

A straight wire of length 3.5 m carries a current and it is placed on a horizontal table in a horizontal uniform magnetic field of 0.14 T.The wire makes an angle of 44^$\circ$ with the magnetic field lines.If the magnitude of the magnetic force on the wire is 9.0 N,what is the current in the wire?

A)36 A
B)42 A
C)48 A
D)67 A
E)26 A

Accepted Answer

The magnetic force on a current-carrying wire is given by F = I * L * B * sin(θ), where I is the current, L is the length of the wire, B is the magnetic field, and θ is the angle between the wire and the magnetic field. Substituting the given values: F = 42 A * 3.5 m * 0.14 T * sin(44°) ≈ 14 N.

Question 8

A straight wire of length 3.5 m carries a current of 42 A and it is placed on a horizontal table in a horizontal uniform magnetic field.The wire makes an angle of 44^$\circ$ with the magnetic field lines.If the magnitude of the magnetic force on the wire is 9.0 N,what is the magnitude of the magnetic field?

A)0.021 T
B)0.067 T
C)0.088 T
D)0.14 T
E)0.23 T

Accepted Answer

The magnetic force on a wire is given by the formula F = BILsinθ, where B is the magnetic field strength, I is the current, L is the length of the wire, and θ is the angle between the wire and the magnetic field lines.

In this case, we are given that F = 9.0 N, I = 42 A, L = 3.5 m, and θ = 44°.

Plugging these values in to the formula, we get:

9.0 N = B(42 A)(3.5 m)sin(44°)

Solving for B, we get:

B = 0.088 T

Therefore, the magnitude of the magnetic field is 0.088 T.

The correct answer is (C).

Question 9

An electron with a speed of 6.00 * 10⁵ m/s enters a uniform magnetic field of 0.0600 T at an angle $\theta$ to the magnetic field lines.The electron will travel in a helical path of radius 4.80 *10^-5 m.Find the angle $\theta$ .

A)25.3^$\circ$
B)32.3^$\circ$
C)57.6^$\circ$
D)61.4^$\circ$

Accepted Answer

We can use the equation for the radius of the helical path:
r = mv⊥/(qB)
where m is the mass of the electron, v⊥ is the component of the velocity perpendicular to the magnetic field (which is equal to v sinθ), q is the charge of the electron, and B is the magnitude of the magnetic field.

We can solve for the angle θ by using the given values for r, v, and B:
sinθ = rB/(mv)
sinθ = (4.80×10^-5 m)(0.0600 T)/[(9.11×10^-31 kg)(6.00×10^7 m/s)]
sinθ = 0.992
θ = sin^-1(0.992)
θ ≈ 57.6°

Therefore, the answer is choice C, 57.6°.

Question 10

In a copper wire,electrons move to the right.The direction of the magnetic field is toward you (out of the page).In which direction is the magnetic force on the copper wire?&#10;A)to the top of the page&#10;B)to the bottom of the page&#10;C)into the page&#10;D)out of the page&#10;E)to the left&#10;

Accepted Answer

The direction of the magnetic force on a current-carrying conductor in a magnetic field can be determined using the right-hand rule. Point your thumb in the direction of the electron flow (to the left, since electrons move opposite to conventional current direction), and your fingers in the direction of the magnetic field (toward you). Your palm then points in the direction of the force, which is up or to the top of the page.

Question 11

A magnetic field is oriented in a certain direction in the horizontal plane.A charged particle travels in a certain direction in the horizontal plane.Given just this information,there&#10;A)is 1 possible direction for the magnetic force on the charged particle.&#10;B)are 2 possible directions for the magnetic force on the charged particle.&#10;C)are four possible directions for the magnetic force on the charged particle.&#10;D)None are correct.&#10;

Accepted Answer

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Question 12

A 30.0 C charged particle moves along the x-axis with a speed of 30.0 m/s.It enters a magnetic field given by .Determine the magnitude of the magnetic force on the particle. A)1.72 * 10^-4 N B)2.31 * 10^-4 N C)4.69 * 10^-4 N D)5.25 * 10^-4 N E)6.34 * 10^-4 N

Accepted Answer

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Question 13

A 3.00 * 10²-eV electron and a 1.00 * 10²-eV electron trapped in a uniform magnetic field move in circular paths in a plane perpendicular to the magnetic field.What is the ratio of the radii of their orbits?

A)1
B)

<strong>A 3.00 * 10<sup>2</sup>-eV electron and a 1.00 * 10<sup>2</sup>-eV electron trapped in a uniform magnetic field move in circular paths in a plane perpendicular to the magnetic field.What is the ratio of the radii of their orbits?</strong> A)1 B) C) D)2 E) <div style=padding-top: 35px>

C)

D)2
E)

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Question 14

A 25-turn square coil with a mass of 0.320 kg and a side of 0.210 m is hinged along a horizontal side,carries a 6.00-A current and is placed in a vertical magnetic field pointing down and having a magnitude of 4.00 mT.Determine the angle that the plane of the coil makes with the vertical when the coil is in equilibrium.Use g = 9.81 m/s².

A)4.6^$\circ$
B)2.3^$\circ$
C)83^$\circ$
D)76^$\circ$
E)12^$\circ$

Accepted Answer

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Question 15

An electron traveling with a velocity of 6.0 * 10⁵ m/s along the direction enters a uniform magnetic field of 0.60 T pointing in the direction.The magnitude of the force on the electron is A)2.6 * 10^-14 N. B)5.8 * 10^-14 N. C)8.5 * 10^-14 N. D)9.4 * 10^-14 N.

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Question 16

An electron is accelerated from rest through a voltage of 600 V.The electron enters a uniform magnetic field of magnitude 5.7 * 10^-2 T and follows a circular path.Determine the radius of the circular path.

A)1.0 * 10^-3 m
B)1.4 * 10^-3 m
C)1.5 * 10^-3 m
D)1.8 * 10^-3 m
E)2.0 * 10^-3 m

Accepted Answer

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Question 17

A straight wire of length 5.0 m carries a current I and it is placed on a horizontal table in a horizontal uniform magnetic field of magnitude 0.016 T.The wire makes an angle of 25^$\circ$ with the magnetic field lines.If the magnitude of the magnetic force on the wire is 0.62 N,what is the current I?

A)35 A
B)18 A
C)45 A
D)24 A
E)65 A

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Question 18

An electron with a speed of 6.00 * 10⁵ m/s enters a uniform magnetic field of 0.0600 T at an angle of 61.4^$\circ$ to the magnetic field lines.The electron will travel in a helical path.Find the radius of the helical path.

A)5.00 * 10^-5 m
B)4.20 * 10^-5 m
C)4.80 * 10^-5 m
D)4.50 * 10^-5 m

Accepted Answer

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Question 19

An electron with a speed of 6.0 * 10⁵ m/s enters a uniform magnetic field of 0.060 T at an angle of 25^$\circ$ to the magnetic field lines.The electron will travel in a helical path.What is the radius of the helical path?

A)1.3 * 10^-5 m
B)2.4 * 10^-5 m
C)4.8 * 10^-5 m
D)5.7 *10^-5 m

Accepted Answer

The answer of An electron with a speed of 6.0...

Question 20

Magnetic field lines always&#10;A)originate at the north poles of magnets and extend to infinity.&#10;B)originate at the south poles of magnets and extend to infinity.&#10;C)form closed loops.&#10;D)None are correct.&#10;

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Question 21

A 0.320 kg,25-turn square coil has a side of 0.210 m,is hinged along a horizontal side and carries a 6.0-A current.When placed in a vertical magnetic field pointing down,the plane of the coil makes a 7.3^$\circ$ angle with the vertical when the coil is in equilibrium.Determine the magnitude of the magnetic field.Use g = 9.81 m/s².

A)8.0 mT
B)6.4 mT
C)2.0 mT
D)4.9 mT
E)4.0 mT

Accepted Answer

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Question 22

The Hall affect is used to measure the carrier density of a thin sheet of electrons.When a current of 80.0 $\mu$ A flows through the length of the electron sheet,which is 1.2-mm long and 0.27-mm wide,a magnetic field of 0.75 T perpendicular to the sheet produces a potential difference of 0.53 mV across the width of the sheet.If the carrier density in the electron sheet is 6.74 * 10²⁵ m^-3,what is the thickness of the sheet?

A)10 nm
B)14 nm
C)9.0 nm
D)8.0 nm
E)12 nm

Accepted Answer

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Question 23

The Hall affect is used to measure the carrier density of a thin sheet of electrons.When a current of 80.0 $\mu$ A flows through the length of the electron sheet,which is 1.2-mm long,0.27-mm wide and 12-nm thick,a magnetic field of 0.75 T perpendicular to the sheet produces a potential difference across the width of the sheet.If the carrier density in the electron sheet is 6.74 * 10²⁵ m^-3,what potential difference is produced across the width of the sheet?

A)0.32 mV
B)0.46 mV
C)0.72 mV
D)0.53 mV
E)0.67 mV

Accepted Answer

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Question 24

A 0.320 kg,25-turn square coil has a side of 0.210 m,is hinged along a horizontal side and carries a current.When placed in a vertical magnetic field pointing down and having a magnitude of 4.00 mT,the plane of the coil makes a 2.3^$\circ$ angle with the vertical when the coil is in equilibrium.Determine the current in the coil.Use g = 9.81 m/s².

A)4.5 A
B)1.5 A
C)6.0 A
D)3.0 A
E)7.5 A

Accepted Answer

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Question 25

One of the first cyclotrons,built by Lawrence and Livingston in the 1930's,accelerated protons circles in the space between two magnetic poles.The magnetic poles were shaped like flat disks with a diameter of 25 cm and the magnetic field between the plates was uniform and oriented perpendicular to the plates.The plates and proton trajectories were horizontal.The plates were parallel to each other and separated by 5 cm.The protons started traveling slowly in small circles at the center of the disks,and would begin making larger and larger circles,travelling faster and faster,until they left the region between the plates.When the protons left the magnetic region at the edge of the plates,they were travelling at 1.2 *10⁷ m/s.What was the magnetic field between the plates?

A)0.50 T
B)0.75 T
C)1.0 T
D)1.25 T
E)1.5 T

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Question 26

A rectangular 30-turn coil of wire,with width of 12.0 cm along the y-axis and height of 25.0 cm along the z-axis,is placed in a uniform external magnetic field with an x-component of 0.0951 T and a y-component of 0.182 T.The coil is hinged along the y-axis and is located in the yz-plane.A current of 0.350 A flows through the wire.What is the magnitude of the torque that B exerts on the coil?

A)0.0250 Nm
B)0.0324 Nm
C)0.0573 Nm
D)0.0647 Nm
E)0.0754 Nm

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Question 27

A charged particle is moving in a uniform,constant magnetic field.Which of the following statements concerning the magnetic force exerted on the particle is(are)not true? (Mark all that are not true.)&#10;A)It does no work on the particle.&#10;B)It may increase the speed of the particle.&#10;C)It may change the velocity of the particle.&#10;D)It does not change the kinetic energy of the particle.&#10;

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Question 28

A proton with an initial velocity of (1.0x + 2.0y + 3.0z)* 10⁵ m/s enters a magnetic field of 0.50z T.Find the magnitude of the acceleration of the proton.The mass of the proton is 1.67 * 10^-27 kg.Where x,y and z are unit vectors in the x,y and z directions,respectively.

A)4.0 * 10¹³ m/s²
B)2.1 * 10¹³ m/s²
C)1.5 * 10¹³ m/s²
D)1.1 * 10¹³ m/s²
E)2.6 * 10¹³ m/s²

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Question 29

A cyclotron with a magnetic field of 9 T is used to accelerate protons with a speed of 50% the speed of light.What is the cyclotron frequency of these protons?&#10;A)225 MHz&#10;B)137 MhZ&#10;C)789 kHz&#10;D)14 Mhz&#10;E)25 kHz&#10;

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Question 30

A proton with an initial velocity of (1.0x + 2.0y + 3.0z)* 10⁵ m/s enters a magnetic field of 0.50z T.Find the magnitude of the acceleration of the proton.The mass of the proton is 1.67 * 10^-27 kg.Where x,y and z are unit vectors in the x,y and z directions,respectively.

A)4.0 * 10¹³ m/s²
B)2.1 * 10¹³ m/s²
C)1.5 * 10¹³ m/s²
D)1.1 * 10¹³ m/s²
E)2.6 * 10¹³ m/s²

Accepted Answer

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Question 31

The Hall affect is used to measure the carrier density of a thin sheet of electrons.When a current of 8.0 $\mu$ A flows through the length of the electron sheet,which is 1.2-mm long,0.27-mm wide and 12-nm thick,a magnetic field of 0.75 T perpendicular to the sheet produces a potential difference of 0.53 mV across the width of the sheet.What is the carrier density in the electron sheet?

A)4.81 * 10¹⁸ m^-3
B)5.90 * 10¹⁹ m^-3
C)2.62 * 10²⁰ m^-3
D)5.90 * 10²⁴ m^-3
E)6.74 * 10²⁵ m^-3

Accepted Answer

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Question 32

An electron enters the region between two plates traveling along the x-direction with a speed of v = 4.78 * 10⁶ m/s.Both plates are parallel to the x-y plane and are separated by 4.5 cm.The potential of the top plate at z = 4.5 cm is +100 V while the potential of the bottom plate at z = 0 cm is 0 V.What is the direction of the magnetic field between the plates that is required so that the electron continues traveling in a straight line along the x-direction in this region?

A)positive y-direction
B)negative y-direction
C)positive z-direction
D)negative z-direction
E)positive x-direction

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Question 33

A 25-turn square coil has a side of 0.210 m,is hinged along a horizontal side and carries a 6.00-A current.When placed in a vertical magnetic field pointing down and having a magnitude of 4.00 mT,the plane of the coil makes a 2.3^$\circ$ angle with the vertical when the coil is in equilibrium.Determine the mass of the coil.Use g = 9.81 m/s².

A)0.452 kg
B)0.640 kg
C)0.320 kg
D)0.785 kg
E)0.904 kg

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Question 34

The Hall affect is used to measure the carrier density of a thin sheet of electrons.When a current flows through the length of the electron sheet,which is 1.2-mm long,0.27-mm wide and 12-nm thick,a magnetic field of 0.75 T perpendicular to the sheet produces a potential difference of 0.53 mV across the width of the sheet.If the carrier density in the electron sheet is 8.49 * 10²⁸ m^-3,what current flows through the length of the sheet?

A)0.12 A
B)1.25 A
C)0.80 A
D)0.36 A
E)0.56 A

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Question 35

A proton with an initial velocity of (1.0x + 2.0y + 3.0z)* 10⁵ m/s enters a magnetic field of 0.50z T.Find the magnitude of the force on the proton.The mass of the proton is 1.67 *10^-27 kg.Where x,y and z are unit vectors in the x,y and z directions,respectively.

A)1.8 * 10^-14 N
B)2.4 * 10^-14 N
C)3.0 * 10^-14 N
D)4.0 * 10^-13 N
E)1.0 * 10^-12 N

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Question 36

Find the magnetic field that produces a maximum torque of 3.14 Nm on a coil of wire with 22 loops a length of 30 cm and a width of 20 cm.The coil has a resistance of 50 ohms and is connected to a 120-V battery.

A)0.020 T
B)0.048 T
C)0.99 T
D)5.7 T
E)22 T

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Question 37

An electron enters the region between two plates traveling along the x-direction with a speed of v = 2.53 * 10⁶ m/s.Both plates are parallel to the x-y plane and are separated by 3.2 cm.The potential of the top plate at z = 3.2 cm is +150 V while the potential of the bottom plate at z = 0 cm is 0 V.What is the magnitude of the magnetic field between the plates that is required so that the electron continues traveling in a straight line along the x-direction in this region?

A)1.85 * 10^-3 T
B)5.93 * 10^-5 T
C)2.63 * 10^-4 T
D)1.32 * 10^-3 T
E)9.45 * 10^-4 T

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Question 38

The Hall affect is used to measure the carrier density of a thin sheet of electrons.When a current of 80.0 $\mu$ A flows through the length of the electron sheet,which is 1.2-mm long,0.27-mm wide and 12-nm thick,a magnetic field perpendicular to the sheet produces a potential difference of 0.53 mV across the width of the sheet.If the carrier density in the electron sheet is 6.74 * 10²⁵ m^-3,what is the magnitude of the magnetic field?

A)1.0 T
B)0.86 T
C)0.75 T
D)1.1 T
E)0.67 T

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Question 39

A proton with an initial velocity of (1.0x + 2.0y + 3.0z)x 10⁵ m/s enters a magnetic field of 0.50z T.Find the radius of the resulting helix.The mass of the proton is 1.67 * 10²⁷ kg.Where x,y and z are unit vectors in the x,y and z directions,respectively.

A)4.7 mm
B)6.3 mm
C)7.8 mm
D)10.mm
E)27 mm

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Question 40

A proton with an initial velocity of (1.0x + 2.0y + 3.0z)* 10⁵ m/s enters a magnetic field of 0.50z T.Find the magnitude of the force on the proton.The mass of the proton is 1.67 *10^-27 kg.Where x,y and z are unit vectors in the x,y and z directions,respectively.

A)1.8 * 10^-14 N
B)2.4 * 10^-14 N
C)3.0 * 10^-14 N
D)4.0 * 10^-13 N
E)1.0 * 10^-12 N

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Question 41

Hall probe is a device widely used for measuring magnetic field strengths.One Hall probe consists of a current carrying strip of bismuth that is 0.20 mm thick and 4 mm wide.The charge carrier density of bismuth is 1.35 * 10²⁵ m^-3.When the strip is placed in a magnetic field perpendicular to the direction of 2.1-A current,it develops a Hall voltage of 3.5 mV across the strip.The strength of the magnetic field is

A)72 T.
B)8 T.
C)1.5 T.
D)0.72 T.
E)21 mT.

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Question 42

Initially at rest,a small copper sphere with a mass of 2.0 * 10^-6 kg and a charge of 3.0 *10^-4 C is accelerated through a 5000 V potential difference before entering a region with a 4.0 T magnetic field that is directed perpendicular to the its velocity.What is the radius of curvature of the copper sphere's motion in the magnetic field region?

A)2.0 m
B)4.1 m
C)8.3 m
D)650 m
E)1300 m

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Question 43

The figure shown depicts the cross section of a current carrying ring of wire having a radius of 4 cm.A 1-A current flows in the ring in the direction indicated in the drawing.The ring is free to rotate,clockwise or counterclockwise,about an axis normal to the page which passes through its center.The ring is connected to a spring with a spring constant of 100 N/m as shown.The spring is fixed to a wall at the other end.When the ring is in the vertical position,the spring is at its natural length.One may assume that the length of the spring is long enough such that any extension or compression follows Hooke's law.If the magnitude of the change in length of the spring when a magnetic field B is applied along the vertical axis is 1.25 mm,what is the magnitude of the magnetic field?

A)4.0 T
B)2.0 T
C)0.50 T
D)1.0 T

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Question 44

The figure shown depicts the cross section of a current carrying ring of wire having a radius of 4 cm.A 1-A current flows in the ring in the direction indicated in the drawing.The ring is free to rotate,clockwise or counterclockwise,about an axis normal to the page which passes through its center.The ring is connected to a spring with a spring constant of 100 N/m as shown.The spring is fixed to a wall at the other end.When the ring is in the vertical position,the spring is at its natural length.One may assume that the length of the spring is long enough such that any extension or compression follows Hooke's law.If the magnitude of the change in length of the spring when a magnetic field B is applied along the vertical axis is 1.25 mm,what is the magnitude of the magnetic field?

A)4.0 T
B)2.0 T
C)0.50 T
D)1.0 T

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Question 45

A 12-V battery is connected to a 4-$\varOmega$ resistor using a rigid rectangular loop of wire.Three meters of wire at the end of the loop extends into a region with a uniform magnetic field of B = 0.2 T directed into the page that has dimensions of 2.0 m * 2.0 m as shown in the figure.What is the net force on the loop?  &#10;A)0.6 N&#10;B)0.8 N&#10;C)1.2 N&#10;D)1.8 N&#10;E)2.4 N&#10;

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Question 46

Which of the following has the largest cyclotron frequency?&#10;A)an electron with velocity v in a magnetic field B&#10;B)a proton with velocity 2 v in a magnetic field 2B&#10;C)a proton with a velocity v in a magnetic field B&#10;D)a proton with a velocity 2 v in a magnetic field B/2&#10;E)a proton with a velocity v/2 in a magnetic field 2B&#10;

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Question 47

A 20-cm long conducting wire of 5-g carrying 5-A current is placed in a uniform magnetic field.The strength and direction of the magnetic field needed to levitate the wire are  &#10;A)49.05 mT into the page.&#10;B)49.05 mT out of the page.&#10;C)25 mT into the page.&#10;D)25 mT out of the page.&#10;E)15 mT into the page.&#10;

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Question 48

A copper wire at the Earth's equator carries a 2340 A current.Assuming that the magnetic field of the earth of 0.5 G at the equator is parallel to the surface of the Earth and that the current flows to the east,what is the largest radius of the wire that can be levitated by the magnetic field?

A)0.50 mm
B)0.44 mm
C)0.36 mm
D)0.65 mm
E)0.73 mm

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The answer of A copper wire at the Earth's equator...

Question 49

Carbon-12 and Carbon-14 atoms,(12 and 14 atomic mass units,respectively)each missing one electron,so that they carry +1e electric charge,pass through a velocity selector (therefore have the same speed)and then pass through a hole in a vertical lead plate into a region of uniform magnetic field,also oriented vertically.What is the ratio of the radii of curvature r₁₂/r₁₄ for these two atoms' paths? A)0.86 B)0.93 C)1.1 D)1.2 E)None are correct.

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Question 50

An electron is traveling horizontally from E to W in a region of space where the Earth's magnetic field is directed horizontally toward the north.What is the direction of the magnetic force on the electron?&#10;A)north&#10;B)south&#10;C)east&#10;D)up&#10;E)down&#10;

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The answer of An electron is traveling horizontally from E...

Question 51

Carbon-12 and Carbon-14 atoms,(12 and 14 atomic mass units,respectively)each missing one electron,so that they carry +1e electric charge,each are accelerated through the same electric potential and pass through a hole in a vertical lead plate into a region of uniform magnetic field,also oriented vertically.What is the ratio of the radii of curvature r₁₂/r₁₄ for these two atoms' paths? A)0.86 B)0.93 C)1.1 D)1.2 E)You would need to know the potential through which they were accelerated.

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Question 52

A positive charge enters a region of uniform magnetic field as shown in the figure.The initial direction of deflection of the charge is  &#10;A)into the page.&#10;B)out of the page.&#10;C)no change in direction and magnitude of the velocity.&#10;D)no change in velocity but it would slow down.&#10;

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Question 53

Thirty turns of wire are tightly wrapped into a coil around a round pencil that has a diameter of 6.0 mm.The pencil is then placed into a uniform B = 8.0 T magnetic field as shown in the figure.If a 4.0-A current is present in the coil of wire,what is the magnitude of the torque on the pencil? A)4.6 * 10^-2 Nm B)7.8 * 10^-2 Nm C)1.4 * 10^-2 Nm D)2.4 * 10^-2 Nm E)18 Nm

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Question 54

The figure shown depicts the cross section of a current carrying ring of wire having a radius of 4 cm.A 1-A current flows in the ring in the direction indicated in the drawing.The ring is free to rotate,clockwise or counterclockwise,about an axis normal to the page which passes through its center.The ring is connected to a spring with a spring constant of 100 N/m as shown.The spring is fixed to a wall at the other end.When the ring is in the vertical position,the spring is at its natural length.One may assume that the length of the spring is long enough such that any extension or compression follows Hooke's law.If the magnitude of the change in length of the spring when a magnetic field B is applied along the vertical axis is 1.25 mm,what is the magnitude of the magnetic field?

A)4.0 T
B)2.0 T
C)0.50 T
D)1.0 T

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The answer of The figure shown depicts the cross section...

Question 55

A straight section of a current-bearing wire passes through a 15-cm wide region of space between the poles of an electromagnet.The magnetic field,when the electromagnet is on,is inclined at a 72 degree angle relative to the wire.If,when the magnet is turned on and produces a field of 1.0 T,the wire experiences a force of 0.18 N,what current is flowing in the wire?&#10;A)1.2 A&#10;B)1.3 A&#10;C)3.7 A&#10;D)3.9 A&#10;E)None are correct.&#10;

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The answer of A straight section of a current-bearing wire...

Question 56

A copper wire of radius 0.5 mm at the Earth's equator carries a current.Assuming that the magnetic field of the earth of 0.5 G at the equator is parallel to the surface of the Earth and that the current flows to the east,what is the current necessary in the wire to allow it to levitate?&#10;A)420 A&#10;B)120 A&#10;C)2340 A&#10;D)1370 A&#10;E)760 A&#10;

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The answer of A copper wire of radius 0.5 mm...

Question 57

A negatively charged particle travelling in the positive y-direction enters an area where a constant magnetic field in the z-direction exists.How will the trajectory of the particle curve?&#10;A)curve is parallel to the x-z plane&#10;B)curve is parallel to the x-y plane&#10;C)curve is parallel to the y-z plane&#10;D)not curve at all&#10;

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The answer of A negatively charged particle travelling in the...

Question 58

A positively charged rod is brought close to a freely suspended compass needle as shown in the figure.The compass needle will  &#10;A)rotate clockwise.&#10;B)rotate counterclockwise.&#10;C)not be affected.&#10;

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The answer of A positively charged rod is brought close...

Question 59

The figure shown depicts the cross section of a current carrying ring of wire having a radius of 4 cm.A 1-A current flows in the ring in the direction indicated in the drawing.The ring is free to rotate,clockwise or counterclockwise,about an axis normal to the page which passes through its center.The ring is connected to a spring with a spring constant of 100 N/m as shown.The spring is fixed to a wall at the other end.When the ring is in the vertical position,the spring is at its natural length.One may assume that the length of the spring is long enough such that any extension or compression follows Hooke's law.If the magnitude of the change in length of the spring when a magnetic field B is applied along the vertical axis is 1.25 mm,what is the magnitude of the magnetic field?

A)4.0 T
B)2.0 T
C)0.50 T
D)1.0 T

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The answer of The figure shown depicts the cross section...

Question 60

A copper wire of length 1 m and diameter 1 mm is oriented such that it is perpendicular to a magnetic field of strength 5 T.The wire carries a current of 3 A across its length.What is the magnitude of the force on this wire?&#10;A)15 N&#10;B)20 N&#10;C)25 N&#10;D)30 N&#10;E)35 N&#10;

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Question 61

A proton and an alpha particle are travelling perpendicular to a magnetic field and make circular orbits or the same radius.The ratio of their speeds v_proton/v_alpha is A)0.5. B)1. C)2. D)4. E)0.25.

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Question 62

The two particles making circular paths in the magnetic field shown have the same mass and kinetic energy.The field is downward into the page.Which of the following statements concerning the particles is correct? A)q₁ and q₂ have same sign;|q₁| > |q₂|. B)q₁ and q₂ have opposite sign;|q₁| > |q₂|. C)q₁ and q₂ have same sign;|q₁| < |q₂|. D)q₁ and q₂ have opposite sign;|q₁| < |q₂|. E)q₁ and q₂ have opposite sign;|q₁| = |q₂|.

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The answer of The two particles making circular paths in...

Question 63

A proton is undergoing uniform circular motion perpendicular to a magnetic field with B = 0.240 T as shown.The linear velocity of the proton is 4.60 * 10⁶ m/s.What is the radius of the orbit of the proton (in m)? The mass of a proton is 1.673 * 10^-27 kg.Ignore any relativistic effects. A)0.123 B)0.139 C)0.157 D)0.177 E)0.200

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The answer of A proton is undergoing uniform circular motion...

Question 64

A proton is in a circular orbit due to a magnetic field of 1.5 mT.What is the orbital frequency? (Note: m_e = 1.67 * 10^-27 kg) A)32.6 MHz B)50.2 Hz C)44.7 mHz D)87.5 µHz E)22.9 kHz

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The answer of A proton is in a circular orbit...

Deck 27: Magnetism