22.8 A straight horizontal wire carries a current of 6.50 μA. An electron is moving above the wire a direction parallel to it and in the
same direction as the conventional current in the wire, at a constant velocity of 5.41×10^5 m/s. Assume that the force of gravity
acts on the electron and that the electron is moving parallel to the Earth's magnetic field, so that the only magnetic force on it
comes from the field generated by the current in the wire. (a) What is the magnitude of the upward force that the magnetic
field must exert on the electron to keep it at a constant velocity? (b) How far is the electron above the wire?
(a) N
(b) m22.9 An electron is initially moving at a speed of 1.79e+3 m/s directly toward a long wire that has 2.00 A of current flowing through
it. The electron is 2.50 m away. What are the direction and amount of the force exerted by the magnetic field on the electron?
N, in the i. opposite
ii. samedirection as the current22.10Four parallel wires are arranged as shown in
the diagram, at the vertices of a square. In
two of them, a 325 mA current flows toward
you, and in the other two the same current
flows away from you. What is the strength of
the magnetic field at the point P, equidistant
from all four wires?
T22.11Two parallel wires are 1.50 m apart. The same amount of current will flow through each. You want a magnetic field of
4.00×10í^5 T at the midpoint between them. (a) Must the currents flow in the same direction, or in opposite directions, through
these wires? (b) How much current must flow in each wire?(a) Same direction Opposite directions
(b) A22.12Three parallel wires are arranged in a partial
square configuration as shown in the diagram.
In two of the wires, a 5.00×10í^4 A current
flows toward you, and in the third wire a
7.50×10í^4 A current flows away from you.
What is the strength of the magnetic field at
the point P, at the "missing corner" of the
square?
T22.13A long wire is placed in a uniform magnetic field whose strength is 0.500 mT. 22.0 A of current flow through the wire, which is
perpendicular to the magnetic field. At point P, the net magnetic field equals zero. How far is point P from the wire?
m
22.14Two parallel long straight wires are oriented in a north-south direction at the same height, 10.0 m apart. The "western" wire
carries 6.00 A of current to the north. The "eastern" wire carries 3.00 A of current, also to the north. There is an imaginary
north-south line somewhere between the wires í not halfway! í where their magnetic fields exactly cancel out. How far is this
imaginary line from the western wire?
m
22.15Two long, straight wires lie on the x and y axes. They conduct currents of 3.00 A and 7.00 A in the positive x and y directions
respectively. What is the direction and strength of the magnetic field generated by the two currents at the point
(í5.00 m, 7.00 m)?
Direction: +x íx +y íy +z íz
Strength: T