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السلام عليكم ورحمة الله وبركاته

بسم الله الرحمن الرحيم

الرجاء مساعدتي على هذي الورقه :mommy_cut: :mommy_cut: :k_crying::k_crying:

[gdwl]http://faculty.ksu.edu.sa/norah/Quizs/Quiz3.doc[/gdwl]

وشكرا

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سااااااااااااااااااااااااااعدوني

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وعليكم السلام ورحمة الله وبركاته

إختي عندي مشكله فاللابتوب بحيث اني ما اقدر انزل ملفات من النت ممكن ترفقين السؤال بس لا هنتي وإن شاء الله نجاوب الأسئلة

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1)The electric flux entering the cube on the right shown below is Ф 20 Nm 2 / C but the flux leaving is only Ф 10 N m 2 / C. Is there charge in the cube and how do you know? If so, how much charge is presen









2) The electric potential is
(A) is simply electrical energy.
(B) is simply electrical charge.
(C) is potential energy per unit charge.
(D) is electrical force per unit charge.
(E) always zero within conductors

3) indicate whether each of the following statements is true (T) or false (F).
a). The electric field of a point charge always points towards the charge. ( )
B ). Regions of zero electrical field intensity need not be regions of zero electrical potential. ( )

4) Gauss’s law shows that the electric field outside a uniformly charged sphere is the
same as the field due to a point charge of the same magnitude at the center of the
sphere. What is the electric potential at the surface of the sphere relative to V = 0 at infinity?


5) A second conducting sphere with inner radius r2 = 12 cm and charge –Q is placed
around the first sphere . How will the charge be distributed on the outer
conductor, and what will be the electric field outside the pair of conductors?


6 ) What is the potential difference between the inner and outer conducting spheres,
assuming the inner radius r2 of the outer sphere is 12 cm?

7) Which of the following best expresses the electric potential a distance d from an electron? (Note e = + 1.6×10 –19 C.)
a. e/4π ε0 d 2
b. –e/4π ε0 d 2
c. e/4π ε0 d
d. –e/4π ε0 d
e. none of the above



8 ) A high voltage (5000 V) line and aground (0 V) line run from Hetch Hetchy reservoir towards Sacramento. The lines are separated by 2.5 m. Which of the following is the best estimate for the electric field at a point directly between the power lines?
a. 0 V/m
b. 2000 V/m pointed towards ground
c. 2000 V/m pointed towards high voltage
d. 12500 V/m pointed towards ground
e. 12500 V/m pointed towards high voltage


9 ) Two parallel plates having charges of equal magnitude but opposite sign are separated by 15.0 cm .The potential difference between each plate is 150V. An electron is released from rest at the negative plate.

a. Calculate the kinetic energy (in electron volts) of the electron just as it reaches the positive plate .


b. Calculate the speed of the electron just as it reaches the positive plate


c. Calculate the acceleration of the electron. Indicate the direction of the acceleration vector relative to the plates

10) A uniformly charged insulating sphere of total charge +q and radius a is placed in the center of a conducting shell of inner radius b and outer radius c. The conducting shell has total charge –q.

Use Gauss’s law to calculate the electric field (magnitude and direction) at r<a





هاذي هي اسئلتها ^ حبيت أساعدك

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مشكوورة إختي هنوده على إرفاقج الأسئلة هنا .

حبيت أسألج في السؤال الأول ممكن ترفقين لي الرسمه للمكعب إذا ما عليج كلافه .


السؤال الأول يتكون من جزئين راح أجاوب على الأول وعقب ما ترفقين الرسمه راح أجاوب ع الثاني مباشره لأن الرسمه مهمه لإجابه الجزء الثاني من السؤال


Question 1 part 1

yes the cube encloses a net charge becaue the net flux is not zero so that means there is a net charge .

part 2

first of all find the flux in both sides shown in the diagram with this equation

[BIMG]http://upload.wikimedia.org/math/9/4/3/94381ead6803920126c150f13c18701a.png[/BIMG]

then add up the both fluxes to get the net flux .

After that use gauss' law to find the charge enclosed by that cube with this equation

[BIMG]http://upload.wikimedia.org/math/c/4/f/c4f04c7069b5e15119a233c0744766f1.png[/BIMG]

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Question 2

The electric potential is the potential energy divided by charge .

V = U/q

So the answer must be number C

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Question 3


the first statment is false because the electric field change its direction according to charge sign for instace the charge is positive then the electric field is radially outward from it and vice versa.

the second statment is correct because E can only be zero if V is constant . they are related in this equation . E = - (dV/dR)

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Question 4

to find the electric potential at the surface of the sphere we have to correlate it with the electric field .
as we found out that electric field outside a sphere is the same electric field found due to a point charge, then we have to find the electric potential due to a point charge in the center of the sphere.

[BIMG]http://up4.m5zn.com/9bjndthcm6y53q1w0kvpz47xgs82rf/2009/12/2/10/pt0w9y3t0.png[/BIMG]

by symmetry, and also by looking at the figure above that V is a function of r only, where r is the radial distance from the origin.

The x-component of the electric field generated along this axis takes the form

[BIMG]http://up4.m5zn.com/9bjndthcm6y53q1w0kvpz47xgs82rf/2009/12/2/10/5on1w09mp.png[/BIMG]

Both the Y- and Z-components of the field are zero.

Both variables are related via [BIMG]http://up4.m5zn.com/9bjndthcm6y53q1w0kvpz47xgs82rf/2009/12/2/10/qfpeahtot.png[/BIMG]


then by integrating we will get [BIMG]http://up4.m5zn.com/9bjndthcm6y53q1w0kvpz47xgs82rf/2009/12/2/10/2tmiwizev.png[/BIMG]

where V0 is an arbitrary constant. Finally, making use of the fact that V = V(r)

[BIMG]http://up4.m5zn.com/9bjndthcm6y53q1w0kvpz47xgs82rf/2009/12/2/10/zmqv5qa19.png[/BIMG]

that is it this a way that we can find the potential at the surface which is the same as we get due to point charge.

I hope this is correct please check first then write it in the answer sheet.

Good luck