Physics
Physics
5th Edition
ISBN: 9781260486919
Author: GIAMBATTISTA
Publisher: MCG
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Chapter 19, Problem 94P

(a)

To determine

The sign of the charge of the ions.

(a)

Expert Solution
Check Mark

Answer to Problem 94P

The sign of the charge of the ions is positive .

Explanation of Solution

The right hand rule states that in the case of a cross product, if the index finger of the right hand points in the direction of the first vector and the second vector points in the direction of the thumb, then the cross product will point in the direction of the thumb. Magnetic Lorentz force on a moving charge is the product of the charge and the cross product of the velocity of the charge and the magnetic field.

Right hand rule for the Lorentz force can be described as if the index finger of the right hand points in the direction of velocity of charge, the middle finger in the direction of the magnetic field, then the thumb will point in the direction of the magnetic force. In the given diagram, the velocity is directed to right, the magnetic field is directed into the page and the force is directed upward. This implies the ion is positive.

(b)

To determine

The accelerating plate which is positively charged.

(b)

Expert Solution
Check Mark

Answer to Problem 94P

The positively charged accelerating plate is west plate .

Explanation of Solution

In part (a), it is found that the ions are positively charged. Positive ions will be attracted by negatively charged plates and will be repelled by positively charged plates. In the given diagram, the ions are accelerated towards the right.

Since the ions are accelerated towards right, the east plate must be negatively charged. This implies the other accelerating plate must be positively charged. Thus the west plate is positively charged.

(c)

To determine

The deflection plate which is positively charged.

(c)

Expert Solution
Check Mark

Answer to Problem 94P

The positively charged deflection plate is north plate .

Explanation of Solution

Right hand rule for the Lorentz force can be described as if the index finger of the right hand points in the direction of velocity of charge, the middle finger in the direction of the magnetic field, then the thumb will point in the direction of the magnetic force. In a mass spectrometer, the correct velocity is selected by making the net force which is the sum of electric and magnetic force on the charge to be zero.

According to the right hand rule, the magnetic force on the positively charged ions is northward between the deflecting plates. To make the net force zero to select the correct velocity, the electric field must be southward. Since electric field points from positive plate to the negative plate, the north plate must be positively charged.

(d)

To determine

The correct values of ΔV1 and ΔV2 in order to count 12C+ ions.

(d)

Expert Solution
Check Mark

Answer to Problem 94P

The value of ΔV1 to count 12C+ ions is 1.6 kV and that of ΔV2 is 320 V .

Explanation of Solution

Write the equation for the magnetic Lorentz force.

F=q(v×B)=qvBsinθ

Here, F is the magnetic Lorentz force, q is the charge of the ion, v is the velocity of the ion, B is the magnetic field and θ is the angle between velocity and the magnetic field

The angle between the magnetic field and the velocity is 90° .

Substitute 90° for θ in the above equation.

F=qvBsin90°=qvB (I)

The magnetic Lorentz force provides the centripetal acceleration required for the semi-circular motion of the ions.

Write the equation for the centripetal force.

Fc=mv2r (II)

Here, Fc is the centripetal force, m is the mass of the ion and r is the radius of the path

Equate equations (I) and (II) and rewrite the equation for v .

qvB=mv2rv=qrBm (III)

Write the equation for a velocity selector.

E=vB

Here, E is the magnitude of the electric field

Put equation (III) in the above equation.

E=(qrBm)B=qrB2m (IV)

Write the equation for the potential difference across the deflecting plates.

ΔV2=Ed

Here, ΔV2 is the potential difference across the deflecting plates and d is the separation between the plates

Put equation (IV) in the above equation.

ΔV2=(qrB2m)d=qrB2dm (V)

Apply the principle of conservation of energy for the given situation.

12mv2=qΔV1

Here, ΔV1 is the potential difference between the charged accelerating plates

Rewrite the above equation for ΔV1 .

ΔV1=mv22q

Put equation (III) in the above equation.

ΔV1=m2q(qrBm)2=qr2B22m (VI)

Conclusion:

Given that the radius of the path is 0.10 m , the value of the magnetic field is 0.20 T and the separation between the deflection plates is 1.00 cm . The charge of the ion is 1.60×1019 C and the mass of the 12C+ ions is 1.993×1026 kg .

Substitute 1.60×1019 C for q , 0.10 m for r , 0.20 T for B , 1.00 cm for d and 1.993×1026 kg for m in equation (V) to find ΔV2 .

ΔV2=(1.60×1019 C)(0.10 m)(0.20 T)2(1.00 cm(1 m100 cm))1.993×1026 kg=(1.60×1019 C)(0.10 m)(0.20 T)2(0.010 m)1.993×1026 kg=320 V

Substitute 1.60×1019 C for q , 0.10 m for r , 0.20 T for B and 1.993×1026 kg for m in equation (VI) to find ΔV1 .

ΔV1=(1.60×1019 C)(0.10 m)2(0.20 T)22(1.993×1026 kg)=(1.60×1019 C)(0.10 m)2(0.20 T)22(1.993×1026 kg)=1.6×103 V=1.6 kV

Therefore, the value of ΔV1 to count 12C+ ions is 1.6 kV and that of ΔV2 is 320 V .

(e)

To determine

The correct values of ΔV1 and ΔV2 in order to count 14C+ ions.

(e)

Expert Solution
Check Mark

Answer to Problem 94P

The value of ΔV1 to count 14C+ ions is 1.4 kV and that of ΔV2 is 280 V .

Explanation of Solution

Equation (VI) and (V) respectively can be used to determine ΔV1 and ΔV2 with the mass of 14C+ ions.

Conclusion:

Given that the mass of the 14C+ ions is 2.325×1026 kg .

Substitute 1.60×1019 C for q , 0.10 m for r , 0.20 T for B and 2.325×1026 kg for m in equation (VI) to find ΔV1 .

ΔV1=(1.60×1019 C)(0.10 m)2(0.20 T)22(2.325×1026 kg)=(1.60×1019 C)(0.10 m)2(0.20 T)22(2.325×1026 kg)=1.4×103 V=1.4 kV

Substitute 1.60×1019 C for q , 0.10 m for r , 0.20 T for B , 1.00 cm for d and 2.325×1026 kg for m in equation (V) to find ΔV2 .

ΔV2=(1.60×1019 C)(0.10 m)(0.20 T)2(1.00 cm(1 m100 cm))2.325×1026 kg=(1.60×1019 C)(0.10 m)(0.20 T)2(0.010 m)2.325×1026 kg=280 V

Therefore, the value of ΔV1 to count 14C+ ions is 1.4 kV and that of ΔV2 is 280 V .

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Chapter 19 Solutions

Physics

Ch. 19.6 - 19.6 Suppose the magnetic field in Fig. 19.28 were...Ch. 19.6 - 19.8 Magnetic Force on a Current-Carrying Wire A...Ch. 19.7 - CHECKPOINT 19.7 Suppose the coil of wire in Fig....Ch. 19.7 - Practice Problem 19.9 Torque on a Coil Starting...Ch. 19.8 - 19.8 What is the direction of the magnetic field...Ch. 19.8 - 19.10 Field Midway Between Two Wires Find the...Ch. 19.9 - Prob. 19.11PPCh. 19 - Prob. 1CQCh. 19 - Prob. 2CQCh. 19 - Prob. 3CQCh. 19 - Prob. 4CQCh. 19 - Prob. 5CQCh. 19 - Prob. 6CQCh. 19 - Prob. 7CQCh. 19 - Prob. 8CQCh. 19 - Prob. 9CQCh. 19 - Prob. 10CQCh. 19 - Prob. 11CQCh. 19 - Prob. 12CQCh. 19 - Prob. 13CQCh. 19 - Prob. 14CQCh. 19 - Prob. 15CQCh. 19 - Prob. 16CQCh. 19 - Prob. 17CQCh. 19 - Prob. 18CQCh. 19 - Prob. 19CQCh. 19 - Prob. 20CQCh. 19 - Prob. 21CQCh. 19 - Prob. 22CQCh. 19 - Prob. 23CQCh. 19 - Prob. 1MCQCh. 19 - Prob. 2MCQCh. 19 - Multiple-Choice Questions 1-4. In the figure, four...Ch. 19 - Prob. 4MCQCh. 19 - Prob. 5MCQCh. 19 - Prob. 6MCQCh. 19 - Prob. 7MCQCh. 19 - Prob. 8MCQCh. 19 - Multiple-Choice Questions 6-9. A wire carries...Ch. 19 - Prob. 10MCQCh. 19 - 11. The magnetic forces that two parallel wires...Ch. 19 - Prob. 12MCQCh. 19 - 1. At which point in the diagram is the magnetic...Ch. 19 - 2. Draw vector arrows to indicate the direction...Ch. 19 - Problems 3-6. Sketch some magnetic field lines for...Ch. 19 - Prob. 4PCh. 19 - Prob. 5PCh. 19 - Problems 3–6. Sketch some magnetic field lines for...Ch. 19 - 7. Find the magnetic force exerted on an electron...Ch. 19 - 8. Find the magnetic force exerted on a proton...Ch. 19 - 9. A uniform magnetic field points north; its...Ch. 19 - 10. A uniform magnetic field points vertically...Ch. 19 - Problems 11-14. Several electrons move at speed...Ch. 19 - 12. Find the magnetic force on the electron at...Ch. 19 - 12. Find the magnetic force on the electron at...Ch. 19 - Problems 11-14. Several electrons move at speed...Ch. 19 - 15. A magnet produces a 0.30 T field between its...Ch. 19 - 16. At a certain point on Earth’s surface in the...Ch. 19 - 17. A cosmic ray muon with the same charge as an...Ch. 19 - 18. In a CRT. electrons moving at 1.8 × 107 m/s...Ch. 19 - 19. A positron (q = +e) moves at 5.0 × 107 m/s in...Ch. 19 - 20. ✦ An electron moves with speed 2.0 × 105 m/s...Ch. 19 - 21. ✦ An electron moves with speed 2.0 × 105 m/s...Ch. 19 - 19.3 Charged Particle Moving Perpendicularly to a...Ch. 19 - 23. Six protons move (at speed v) in magnetic...Ch. 19 - 24. An electron moves at speed 8.0 × 105 m/s in a...Ch. 19 - 25. The magnetic field in a hospital’s cyclotron...Ch. 19 - 26. The magnetic field in a cyclotron used in...Ch. 19 - 27. The magnetic field in a cyclotron used to...Ch. 19 - 28. A beam of α particles (helium nuclei) is used...Ch. 19 - 29. A singly charged ion of unknown mass moves in...Ch. 19 - 30. In one type of mass spectrometer, ions having...Ch. 19 - 31. Natural carbon consists of two different...Ch. 19 - 32. After being accelerated through a potential...Ch. 19 - 33. A sample containing carbon (atomic mass 12 u),...Ch. 19 - Prob. 34PCh. 19 - 35. Show that the time for one revolution of a...Ch. 19 - 36. Crossed electric and magnetic fields are...Ch. 19 - 37. A current I = 40.0 A flows through a strip of...Ch. 19 - 38. In Problem 37, if the width of the strip is...Ch. 19 - 39. In Problem 37, the width of the strip is 3.5...Ch. 19 - 40. The strip in the diagram is used as a Hall...Ch. 19 - 41. A strip of copper 2.0 cm wide carries a...Ch. 19 - Prob. 42PCh. 19 - 43. An electromagnetic flowmeter is used to...Ch. 19 - 44. A charged particle is accelerated from rest...Ch. 19 - 45. A straight wire segment of length 0.60 m...Ch. 19 - 46. A straight wire segment of length 25 cm...Ch. 19 - 47. Parallel conducting tracks, separated by 2.0...Ch. 19 - 48. An electromagnetic rail gun can fire a...Ch. 19 - 49. A straight, stiff wire of length 1.00 m and...Ch. 19 - Prob. 50PCh. 19 - Prob. 51PCh. 19 - Prob. 52PCh. 19 - 53. ✦ A straight wire is aligned east-west in a...Ch. 19 - 54. A straight wire is aligned north-south in a...Ch. 19 - 55. In each of six electric motors, a cylindrical...Ch. 19 - 56. In an electric motor, a circular coil with...Ch. 19 - 57. In an electric motor, a coil with 100 turns of...Ch. 19 - 58. A square loop of wire of side 3.0 cm carries...Ch. 19 - 59. The intrinsic magnetic dipole moment of the...Ch. 19 - 60. In a simple model, the electron in a hydrogen...Ch. 19 - 61. A certain fixed length L of wire carries a...Ch. 19 - 62. Use the following method to show that the...Ch. 19 - 63. A square loop of wire with side 0.60 m carries...Ch. 19 - Prob. 64PCh. 19 - 65. Estimate the magnetic field at distances of...Ch. 19 - Prob. 66PCh. 19 - 67. Kieran measures the magnetic field of an...Ch. 19 - 68. Two wires each carry 10.0 A of current (in...Ch. 19 - In Problem 67, what is the magnetic field at a...Ch. 19 - What is the magnetic field at point P if the...Ch. 19 - 70. Point P is midway between two long, straight,...Ch. 19 - 70. Point P is midway between two long, straight,...Ch. 19 - Prob. 72PCh. 19 - Prob. 73PCh. 19 - 74. Two long straight wires carry the same amount...Ch. 19 - 75. In Problem 74, find the magnetic field at...Ch. 19 - 76. In Problem 74, find the magnetic field at...Ch. 19 - 77. A solenoid of length 0.256 m and radius 2.0 cm...Ch. 19 - 78. Two long straight parallel wires separated by...Ch. 19 - Prob. 79PCh. 19 - Two concentric circular wire loops in the same...Ch. 19 - 81. You are designing the main solenoid for an MRI...Ch. 19 - 82. A solenoid has 4850 turns per meter and radius...Ch. 19 - 83. Find the magnetic field at the center of the...Ch. 19 - 84. Find the magnetic field at point P, the...Ch. 19 - Prob. 85PCh. 19 - Prob. 86PCh. 19 - Prob. 87PCh. 19 - 88. A number of wires carry currents into or out...Ch. 19 - 89. ✦ An infinitely long, thick cylindrical shell...Ch. 19 - 90. In this problem, use Ampère’s law to show...Ch. 19 - Prob. 91PCh. 19 - Prob. 92PCh. 19 - Prob. 93PCh. 19 - Prob. 94PCh. 19 - Prob. 95PCh. 19 - Prob. 96PCh. 19 - Prob. 97PCh. 19 - Prob. 98PCh. 19 - Prob. 99PCh. 19 - Prob. 100PCh. 19 - Prob. 101PCh. 19 - Prob. 102PCh. 19 - Prob. 103PCh. 19 - Prob. 104PCh. 19 - Prob. 105PCh. 19 - 106. Two conducting wires perpendicular to the...Ch. 19 - Prob. 107PCh. 19 - Prob. 108PCh. 19 - 110. A solenoid with 8500 turns per meter has...Ch. 19 - Prob. 109PCh. 19 - Prob. 111PCh. 19 - Prob. 115PCh. 19 - Prob. 112PCh. 19 - Prob. 113PCh. 19 - Prob. 114PCh. 19 - Prob. 117PCh. 19 - Prob. 116PCh. 19 - Prob. 118PCh. 19 - Prob. 120PCh. 19 - Prob. 121PCh. 19 - Prob. 122PCh. 19 - Prob. 123PCh. 19 - Prob. 124PCh. 19 - Prob. 125PCh. 19 - Prob. 126PCh. 19 - Prob. 127PCh. 19 - Prob. 128P
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