a spherical gaussian surface (#1) encloses and is centered...

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A spherical Gaussian surface (#1) encloses and is centered on a point charge +q. A second spherical Gaussian surface (#2) of the same size also encloses the charge but is not centered on it. Compared to the electric ux through surface #1, the ux through surface #2 is A. greater. B. the same. C. less, but not zero. D. zero. E. not enough information given to decide Q22.1 +q Gaussian surface #1 Gaussian surface #2

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Page 1: A spherical Gaussian surface (#1) encloses and is centered ...plam/ph272_summer/L2/22_ClickerQuestions_Lam.pdfA spherical Gaussian surface (#1) encloses and is centered on a point

A spherical Gaussian surface (#1)encloses and is centered on a pointcharge +q. A second sphericalGaussian surface (#2) of the samesize also encloses the charge but isnot centered on it.

Compared to the electric fluxthrough surface #1, the flux throughsurface #2 is

A. greater. B. the same.

C. less, but not zero. D. zero.

E. not enough information given todecide

Q22.1

+q

Gaussiansurface #1

Gaussiansurface #2

Page 2: A spherical Gaussian surface (#1) encloses and is centered ...plam/ph272_summer/L2/22_ClickerQuestions_Lam.pdfA spherical Gaussian surface (#1) encloses and is centered on a point

A spherical Gaussian surface (#1)encloses and is centered on a pointcharge +q. A second sphericalGaussian surface (#2) of the samesize also encloses the charge but isnot centered on it.

Compared to the electric fluxthrough surface #1, the flux throughsurface #2 is

A. greater. B. the same.

C. less, but not zero. D. zero.

E. not enough information given todecide

A22.1

+q

Gaussiansurface #1

Gaussiansurface #2

Page 3: A spherical Gaussian surface (#1) encloses and is centered ...plam/ph272_summer/L2/22_ClickerQuestions_Lam.pdfA spherical Gaussian surface (#1) encloses and is centered on a point

Two point charges,+q (in red) and –q(in blue), arearranged as shown.

Through whichclosed surface(s) isthe net electric fluxequal to zero?

A. surface A only B. surface B only

C. surface C only C. surface D only

D. both surface C and surface D

Q22.2

Page 4: A spherical Gaussian surface (#1) encloses and is centered ...plam/ph272_summer/L2/22_ClickerQuestions_Lam.pdfA spherical Gaussian surface (#1) encloses and is centered on a point

Two point charges,+q (in red) and –q(in blue), arearranged as shown.

Through whichclosed surface(s) isthe net electric fluxequal to zero?

A. surface A only B. surface B only

C. surface C only C. surface D only

D. both surface C and surface D

A22.2

Page 5: A spherical Gaussian surface (#1) encloses and is centered ...plam/ph272_summer/L2/22_ClickerQuestions_Lam.pdfA spherical Gaussian surface (#1) encloses and is centered on a point

A conducting spherical shell with innerradius a and outer radius b has apositive point charge Q located at itscenter. The total charge on the shell is–3Q, and it is insulated from itssurroundings. In the region a < r < b,

A. the electric field points radially outward.

B. the electric field points radially inward.

C. is zero.

D. not enough information given to decide

Q22.3

Page 6: A spherical Gaussian surface (#1) encloses and is centered ...plam/ph272_summer/L2/22_ClickerQuestions_Lam.pdfA spherical Gaussian surface (#1) encloses and is centered on a point

A conducting spherical shell with innerradius a and outer radius b has apositive point charge Q located at itscenter. The total charge on the shell is–3Q, and it is insulated from itssurroundings. In the region a < r < b,

A. the electric field points radially outward.

B. the electric field points radially inward.

C. is zero.

D. not enough information given to decide

A22.3

Page 7: A spherical Gaussian surface (#1) encloses and is centered ...plam/ph272_summer/L2/22_ClickerQuestions_Lam.pdfA spherical Gaussian surface (#1) encloses and is centered on a point

A conducting spherical shell with innerradius a and outer radius b has apositive point charge Q located at itscenter. The total charge on the shell is–3Q, and it is insulated from itssurroundings. How much charge residesin the inner surface (r=a)?

A. zero.

B. -1.5 Q .

C. - Q.

D. not enough information given to decide

Q22.4

Page 8: A spherical Gaussian surface (#1) encloses and is centered ...plam/ph272_summer/L2/22_ClickerQuestions_Lam.pdfA spherical Gaussian surface (#1) encloses and is centered on a point

A conducting spherical shell with innerradius a and outer radius b has apositive point charge Q located at itscenter. The total charge on the shell is–3Q, and it is insulated from itssurroundings. How much charge residesin the inner surface (r=a)?

A. zero.

B. -1.5 Q .

C. - Q.

D. not enough information given to decide

A22.4

Page 9: A spherical Gaussian surface (#1) encloses and is centered ...plam/ph272_summer/L2/22_ClickerQuestions_Lam.pdfA spherical Gaussian surface (#1) encloses and is centered on a point

A conducting spherical shell with innerradius a and outer radius b has a positivepoint charge Q located at its center. Thetotal charge on the shell is –3Q, and it isinsulated from its surroundings. What isthe force on a test charge (q) locatedoutside the shell at the distance r fromthe center (r > b) ?

A. zero.

B. kqQ/r2, pointing outward

C. kq(3Q)/r2 , pointing inward

D. kq(2Q)/r2 , pointing inward

Q22.5

Page 10: A spherical Gaussian surface (#1) encloses and is centered ...plam/ph272_summer/L2/22_ClickerQuestions_Lam.pdfA spherical Gaussian surface (#1) encloses and is centered on a point

A conducting spherical shell with innerradius a and outer radius b has a positivepoint charge Q located at its center. Thetotal charge on the shell is –3Q, and it isinsulated from its surroundings. What isthe force on a test charge (q) locatedoutside the shell at the distance r fromthe center (r > b) ?

A. zero.

B. kqQ/r2, pointing outward

C. kq(3Q)/r2 , pointing inward

D. kq(2Q)/r2 , pointing inward

A22.5

Page 11: A spherical Gaussian surface (#1) encloses and is centered ...plam/ph272_summer/L2/22_ClickerQuestions_Lam.pdfA spherical Gaussian surface (#1) encloses and is centered on a point

A conducting spherical shell with innerradius a and outer radius b has a positivepoint charge Q located at off-center. Thetotal charge on the shell is –3Q, and it isinsulated from its surroundings. What isthe force on a test charge (q) locatedoutside the shell at the distance r fromthe center (r > b) ?

A. Not enough information to decide

B. kqQ/r2, pointing outward

C. kq(3Q)/r2 , pointing inward

D. kq(2Q)/r2 , pointing inward

Q22.6

Page 12: A spherical Gaussian surface (#1) encloses and is centered ...plam/ph272_summer/L2/22_ClickerQuestions_Lam.pdfA spherical Gaussian surface (#1) encloses and is centered on a point

A conducting spherical shell with innerradius a and outer radius b has a positivepoint charge Q located at off-center. Thetotal charge on the shell is –3Q, and it isinsulated from its surroundings. What isthe force on a test charge (q) locatedoutside the shell at the distance r fromthe center (r > b) ?

A. Not enough information to decide

B. kqQ/r2, pointing outward

C. kq(3Q)/r2 , pointing inward

D. kq(2Q)/r2 , pointing inward

A22.6

Page 13: A spherical Gaussian surface (#1) encloses and is centered ...plam/ph272_summer/L2/22_ClickerQuestions_Lam.pdfA spherical Gaussian surface (#1) encloses and is centered on a point

For which of the following charge distributions wouldGauss’s law not be useful for calculating the electric field?

A. a uniformly charged sphere of radius R

B. a spherical shell of radius R with charge uniformlydistributed over its surface

C. a circular cylinder of radius R and height h withcharge uniformly distributed over its surface

D. an infinitely long circular cylinder of radius R withcharge uniformly distributed over its surface

E. Gauss’s law would be useful for finding the electricfield in all of these cases.

Q22.7

Page 14: A spherical Gaussian surface (#1) encloses and is centered ...plam/ph272_summer/L2/22_ClickerQuestions_Lam.pdfA spherical Gaussian surface (#1) encloses and is centered on a point

For which of the following charge distributions wouldGauss’s law not be useful for calculating the electric field?

A. a uniformly charged sphere of radius R

B. a spherical shell of radius R with charge uniformlydistributed over its surface

C. a circular cylinder of radius R and height h withcharge uniformly distributed over its surface

D. an infinitely long circular cylinder of radius R withcharge uniformly distributed over its surface

E. Gauss’s law would be useful for finding the electricfield in all of these cases.

A22.7