QATAR UNIVERSITY College of Arts & Sciences Department of Mathematics, Statistics and Physics

General Physics II (Phys 193) Quiz-1 (5 Points)

Fall 2011 - Time allowed: 50 Minutes

Student Name _______________________________Student Name ________________________________Student Name ________________________________Student Name ________________________________Group: _________________________________

These are the fields outside and inside a sphere respectively.

MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question and writeyour justifications.

1) The electric field in a region of space is oriented along the positive y axis. A circle of radius R isplaced in the xz-plane. The flux of the electric field through this circle is . The same electric fieldpassing through a second circle of radius 2R parallel to xz-plane would result in a flux equal to

1)

A) 3 . B) 2 . C) 0. D) . E) 4 . ___________________________________________________________________________________ _________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________

FIGURE 22-1

2) Fig. 22-1 shows four Gaussian surfaces surrounding a distribution of charges. Which Gaussiansurfaces have an electric flux of +q/ o through them?

2)

A) a. B) b. C) b and c. D) c. E) b and d.___________________________________________________________________________________ _________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

3) Two long straight parallel lines of charge, #1 and #2, carry positive charge per unit lengths of 1and 2, respectively. 1 > 2. The locus of points where the electric field is zero in this case is

3)

A) along line #1.B) along a line between the lines closer to line #2 than line #1.C) at a point halfway between the lines.D) along a line between the lines closer to line #1 than line #2.E) cannot be determined

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FIGURE 22-2

4) A uniform electric field with a magnitude of 6 × 106 N/C is applied to a cube of edge length 0.1 mas shown in Fig. 22-2. If the direction of the E-field is along the +x-axis, what is the electric fluxpassing through the shaded face of the cube?

4)

A) 600 × 104 Nm2/CB) 0.6 × 104 Nm2/CC) 6000 × 104 Nm2/CD) 6 × 104 Nm2/CE) 60 × 104 Nm2/C

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5) A solid non-conducting sphere of radius R carries a uniform charge density. At a radial distance r1= R/4 the electric field has a magnitude E0. What is the magnitude of the electric field at a radialdistance r2 = 2R?

5)

A) E0 B) 0 C) E0/4 D) E0/2 E) 2E0___________________________________________________________________________________ _________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

6) For a proton moving in the direction of the electric field 6)A) its potential energy increases and its electric potential increases.B) both its potential energy and it electric potential remain constant.C) its potential energy decreases and its electric potential increases.D) its potential energy increases and its electric potential decreases.E) its potential energy decreases and its electric potential decreases.

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7) The potential of a uniformly charged sphere is lowest at 7)A) a distance from the sphere equal to its radius.B) the surface of the sphere.C) the center of the sphere.D) infinity.E) a distance from the sphere equal to its diameter.

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8) A negative charge is moved from point A to point B along an equipotential surface. Which of thefollowing statements is true for this case?

8)

A) The negative charge performs work in moving from point A to point B.B) Work is required to move the negative charge from point A to point B.C) No work is required to move the negative charge from point A to point B.D) Not enough information is given to make a statement about the work involved.E) Work is both required and performed in moving the negative charge from point A to point B.

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FIGURE 23-11

9) Fig. 23-11 shows the variation of the electric potential V (measured in Volts) as a function of theradial direction r (measured in meters). For which range of r is the magnitude of the electric fieldthe largest?

9)

A) from r = 0 to r = 2 mB) from r = 4 m to r = 6 mC) The magnitude of the field is the same everywhere.D) from r = 2 m to r = 4 mE) More information is needed to answer the question.

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SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question and show steps.

10) Three electric charges QA= q, QB = -q, and QC = -2q are located at the points A (x = + a, y= 0), B (x = -a, y = 0), and C (x = 0, y = +2a) respectively. What is the value of the electricpotential at the origin?

10)

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1) E

2) B

3) B

4) D

5) A

6) E

7) D

8) C

9) D

10) -