CALC A long, straight wire with a circular cross section of radius R carries a current I . Assume that the current density is not constant across the cross section of the wire, but rather varies as J = αr , where α is a constant, (a) By the requirement that J integrated over the cross section of the wire gives the total current I , calculate the constant α in terms of I and R . (b) Use Ampere’s law to calculate the magnetic field B ( r ) for (i) r ≤ R and (ii) r ≥ R . Express your answers in terms of I .
CALC A long, straight wire with a circular cross section of radius R carries a current I . Assume that the current density is not constant across the cross section of the wire, but rather varies as J = αr , where α is a constant, (a) By the requirement that J integrated over the cross section of the wire gives the total current I , calculate the constant α in terms of I and R . (b) Use Ampere’s law to calculate the magnetic field B ( r ) for (i) r ≤ R and (ii) r ≥ R . Express your answers in terms of I .
CALC A long, straight wire with a circular cross section of radius R carries a current I. Assume that the current density is not constant across the cross section of the wire, but rather varies as J = αr, where α is a constant, (a) By the requirement that J integrated over the cross section of the wire gives the total current I, calculate the constant α in terms of I and R. (b) Use Ampere’s law to calculate the magnetic field B(r) for (i) r ≤ R and (ii) r ≥ R. Express your answers in terms of I.
1. A charge of -25 μC is distributed uniformly throughout a spherical volume of radius 11.5 cm.
Determine the electric field due to this charge at a distance of (a) 2 cm, (b) 4.6 cm, and (c) 25 cm from
the center of the sphere.
(a) =
=
(b) E =
(c)Ẻ =
=
NC NC NC
1.
A long silver rod of radius 3.5 cm has a charge of -3.9
ис
on its surface. Here ŕ is a unit vector
ст
directed perpendicularly away from the axis of the rod as shown in the figure.
(a) Find the electric field at a point 5 cm from the center of the rod (an outside point).
E =
N
C
(b) Find the electric field at a point 1.8 cm from the center of the rod (an inside point)
E=0
Think & Prepare
N
C
1. Is there a symmetry in the charge distribution? What kind of symmetry?
2. The problem gives the charge per unit length 1. How do you figure out the surface charge density σ
from a?
1. Determine the electric flux through each surface whose cross-section is shown below.
55
S₂
-29
S5
SA
S3
+ 9
Enter your answer in terms of q and ε
Φ
(a) s₁
(b) s₂
=
-29
(C) Φ
զ
Ερ
(d) SA
=
(e) $5
(f) Sa
$6
=
II
✓
-29
S6
+39
Chapter 28 Solutions
University Physics with Modern Physics (14th Edition)
Chemistry: An Introduction to General, Organic, and Biological Chemistry (13th Edition)
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