Exercise 27.12 A horizontal rectangular surface has dimensions 2.85 by 3.40 and is in a uniform magnetic field that is directed at an angle of 26.0 above the horizontal. Part A What must the magnitude of the magnetic field be to produce a flux of 3.20 10 through the surface?

Exercise 27.12
A horizontal rectangular surface has dimensions 2.85 by 3.40 and is in a uniform magnetic field that is directed at an angle of 26.0 above the horizontal.
Part A
What must the magnitude of the magnetic field be to produce a flux of 3.20 10 through the surface?
Express your answer with the appropriate units.
ANSWER:
Exercise 27.22
In a cyclotron, the orbital radius of protons with energy 300 is 16.0 . You are redesigning the cyclotron to be used instead for alpha particles with energy 300 . An alpha particle has charge 2e and mass 6.64 10 .
Part A
If the magnetic field isn t changed, what will be the orbital radius of the alpha particles?
Express your answer to three significant figures and include the appropriate units.
ANSWER:
Exercise 27.28
Part A
What is the speed of a beam of electrons when the simultaneous influence of an electric field of and a magnetic field of , with both fields normal to the beam and to each other, produces no deflection of the electrons?
ANSWER:
Part B
When the electric field is removed, what is the radius of the electron orbit?
cm cm ∘
× −4 Wb
= B
keV cm keV q = + m = × kg−27
= Rα
1.56 × V/m104
4.62 × T10−3
= v m/s
ANSWER:
Part C
What is the period of the orbit?
ANSWER:
Exercise 27.36
An electromagnet produces a magnetic field of 0.590 in a cylindrical region of radius 2.90 between its poles. A straight wire carrying a current of 10.7 passes through the center of this region and is perpendicular to both the axis of the cylindrical region and the magnetic field.
Part A
What magnitude of force is exerted on the wire?
ANSWER:
Exercise 27.46
A coil with a magnetic moment of 1.50 is oriented initially with its magnetic moment antiparallel to a uniform magnetic field of magnitude 0.845 .
Part A
What is the change in potential energy of the coil when it is rotated 180 so that its magnetic moment is parallel to the field?
ANSWER:
Prelecture Concept Question 27.05
Part A
A charged particle enters into a uniform magnetic field such that its velocity vector is perpendicular to the magnetic field vector. Ignoring the particle’s weight, what type of path will the particle follow?
ANSWER:
= R m
= T s
T cm A
= F N
A ⋅ m2
T
∘
= U J
Conceptual Question 27.07
Part A
A vertical wire carries a current vertically upward in a region where the magnetic field vector points toward the north. What is the direction of the magnetic force on this current due to the field?
ANSWER:
Prelecture Concept Question 27.01
Part A
Which of the following statements are true?
Check all that apply.
ANSWER:
The charged particle will follow a circular path.
The charged particle will follow a straight-line path.
The charged particle will follow a parabolic path.
The charged particle will follow a spiral path.
downward
toward the north
toward the south
toward the west
toward the east
Scientists have evidence that single isolated magnetic poles, called magnetic monopoles, exist.
The north pole of a bar magnet will attract the south pole of another bar magnet.
Earth’s geographic south pole is also a magnetic south pole.
The south poles of two bar magnets will repel each other.
Earth’s geographic north pole is actually a magnetic south pole.
The north poles of two bar magnets will attract each other.
Prelecture Concept Question 27.03
Part A
Consider a magnetic force acting on an electric charge in a uniform magnetic field. Which of the following statements are true?
Check all that apply.
ANSWER:
Conceptual Question 27.05
Part A
Ions having equal charges but masses of and 2 are accelerated through the same potential difference and then enter a uniform magnetic field perpendicular to their path. If the heavier ions follow a circular arc of radius , what is the radius of the arc followed by the lighter?
ANSWER:
Conceptual Question 27.01
The direction of the magnetic force acting on a moving charge in a magnetic field is perpendicular to the direction of the magnetic field.
A magnetic force is exerted on a stationary electric charge in a uniform magnetic field.
A magnetic force is exerted on an electric charge moving through a uniform magnetic field.
An electric charge moving parallel to a magnetic field experiences a magnetic force.
The direction of the magnetic force acting on a moving electric charge in a magnetic field is perpendicular to the direction of motion.
An electric charge moving perpendicular to a magnetic field experiences a magnetic force.
M M R
3R
/R 2√
4R
2√ R
/2R
Part A
An electron moving in the direction of the + -axis enters a magnetic field. If the electron experiences a magnetic deflection in the – direction, the direction of the magnetic field in this region points in the direction of the
ANSWER:
Problem 27.24
Part A
A straight 15.0-g wire that is 2.00 m long carries a current of 8.00 A. This wire is aligned horizontally along the west-east direction with the current going from west to east. You want to support the wire against gravity using the weakest possible uniform external magnetic field.
(a) Which way should the magnetic field point?
ANSWER:
Part B
(b) What is the magnitude of the weakest possible magnetic field you could use?
ANSWER:
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x y
– -axis.x
+z-axis.
– -axis.z
+y-axis.
– -axis.y
from east to west
from west to east
from south to north
from north to south
none of the above