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A proton is moving to the right in a
vertical electric field. A short time
later, the proton’s velocity is
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Which electric field is responsible for the proton’s
trajectory?
A.
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B.
C.
D.
E.
Flux Corresponds to Amount of “fluid mass”
Passing Through Area Per Unit Time
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The electric flux through the shaded surface is
A. 0.
B. 200 N m/C.
C. 400 N m2/C.
D. Flux isn’t defined
for an open
surface.
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The electric flux through the shaded surface is
A. 0.
B. 400cos20 N m2/C.
C. 400cos70 N m2/C.
D. 400 N m2/C.
E. Some other value.
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Which surface, A or B, has
the larger electric flux?
A. Surface A has more flux.
B. Surface B has more flux.
C. The fluxes are equal.
D. It’s impossible to say without knowing
more about the electric field.
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Surfaces A and B have
the same shape and the
same area. Which has
the larger electric flux?
A. Surface A has more flux.
B. Surface B has more flux.
C. The fluxes are equal.
D. It’s impossible to say without knowing
more about the electric field.
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Assigning Normal Area Vectors to
Small Patches of Closed Surface
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Quick Proof of Gauss's Law
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These are cross sections of 3D closed surfaces. The top and
bottom surfaces, which are flat, are in front of and behind the
screen. The electric field is everywhere parallel to the screen.
Which closed surface or surfaces have zero electric flux?
A.
B.
C.
D.
E.
Surface A.
Surface B.
Surface C.
Surfaces B and C .
All three surfaces.
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The electric field is constant
over each face of the box.
The box contains
A. Positive charge.
B. Negative charge.
C. No net charge.
D. Not enough information to tell.
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Slide 27-69
Which spherical Gaussian surface
has the larger electric flux?
A. Surface A.
B. Surface B.
C. They have the same flux.
D. Not enough information to tell.
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Spherical Gaussian surfaces of
equal radius R surround two
spheres of equal charge Q.
Which Gaussian surface has
the larger electric field?
A. Surface A.
B. Surface B.
C. They have the same electric field.
D. Not enough information to tell.
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A spherical Gaussian surface
surrounds an electric dipole.
The net enclosed charge is
zero. Which is true?
A. The electric field is
zero everywhere on
the Gaussian surface.
B. The electric field is not
zero everywhere on the Gaussian surface.
C. Whether or not the field is zero on the surface
depends on where the dipole is inside the sphere.
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A spherical Gaussian surface
surrounds an electric dipole.
The net enclosed charge is
zero. Which is true?
A. The electric field is
zero everywhere on
the Gaussian surface.
B. The electric field is not
zero everywhere on the Gaussian surface.
C. Whether or not the field is zero on the surface
depends on where the dipole is inside the sphere.
The flux is zero, but that doesn’t require the field to be zero.
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Slide 27-78
The electric flux is shown through
two Gaussian surfaces. In terms
of q, what are charges q1 and q2?
A.
q1 = 2q; q2 = q.
B.
q1 = q; q2 = 2q.
C.
q1 = 2q; q2 = –q.
D.
q1 = 2q; q2 = –2q.
E.
q1 = q/2; q2 = q/2.
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A cylindrical Gaussian surface
surrounds an infinite line of charge.
The flux e through the two flat
ends of the cylinder is
A.
0.
B.
2  2rE.
C.
2  r2E.
D.
2  rLE.
E.
It will require an integration to find out.
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A cylindrical Gaussian surface
surrounds an infinite line of charge.
The flux e through the wall
of the cylinder is
A.
0.
B.
2rLE
C.
r2LE.
D.
rLE.
E.
It will require an integration to find out.
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© 2013 Pearson Education, Inc.