Physics 202

Example of Mid-Term exam with solution

عزيزي الطالب: لكي تتم الاستفادة من هذا الاختبار لا تنظر في الحل الآن وإنما حل الاختبار أولا في الوقت المحدد وهو 90 دقيقة  ثم صحح اختبارك بنفسك وذلك بمقارنته مع الإجابات الصحيحة. ثم بعد ذلك أنظر في طرقة حل النموذج وقارنه بطريقة حلك. وبذلك تستفيد مستقبلا من تدارك الأخطاء التي قد تكون وقعت فيها

PHYSICS   202

MID - TERM EXAM

TIME 90 MIN.

Encircle The Correct Answer

Note:   e = 1.6 ´ 10-19 C,

e0 = 8.85 ´ 10-12 C2/N.m2

k = 9 ´ 109 N.m2/C2

1) Two charges q₁ = 8 mC and q₂ = 2 mC are separated by 3  m. A third charge (q₃) is placed  a distance  r  from q₁ such that the resultant electric force on q₃ is zero. The distance  r  is

a) 1m               b) 2m              c)  3 m             d) 4 m             e) 5 m 

2) Three charges q₁ = 1.3 mC, q₂ = 2.5 m C, and q₃ = 3.2 mC are located as shown in figure 1. The magnitude of the net electric force on q is

a) 85 mN            b) 149 mN          c) 149 N          d) 85 N           e) Zero

3) Two charges q₁ = 1.4  nC and q₂ = -1.4  nC are located at two corners of a square of side 3 m as shown in figure 2. The magnitude of the electric field at any of the other two corners is

a)      6 N/C      b) 4 N/C       c) 8 N/C        d) 2 N/C       e)   Zero        

4) An electron with a speed of 3 ´ 10⁶ m/s and mass 9.1 ´ 10^{-31 kg moves into a uniform electric field of 3200 N/C. The field is parallel to the electron’s velocity and acts to decelerate the electron. The distance traveled by the electron before it comes to rest is}

  a)  8 cm            b) 8m          c) 8 mm            d) 8 km          e) 8 mm

5) In a uniform electric field, the potential at a point p₁ is V₁ = - 50 V, and the potential at a point p₂ is V₂ = 150 V. The work done by an external force in moving a charge q = 5 m C from p₂ to p₁ is

a)      3 mJ             b) 3 J           c) 1 J           d) - 34 J           e) 1 mJ

6) A metallic sphere of radius 30 cm has a charge of 3 mC. The electric potential at a point 15 cm from the center is

a) 9 ´ 10⁴ V     b) 3 ´ 10⁴ V     c) 36 ´ 10⁴ V     d) 18 ´ 10⁴ V    e) Zero

7) A conducting sphere of radius 30 cm has a charge of 3 mC. The electric field at a distance 15 cm from the center of the sphere is

a) 3´10⁵ N/C   b) 6´10⁵ N/C    c) 9´10⁵ N/C    d) 12´10⁵ N/C    e) Zero

8) The electric field due to a charged copper wire was found to be 1.8 ´ 10⁵ N/C at a  distance of 0.1 m from the axis of the wire. The linear density of charge along the wire is

a) 10 mC/m     b) 100 mC/m    c) 1mC/m     d) 25 mC/m    e) 50 mC/m

9) A certain charge Q is enclosed by a spherical Gaussian surface of radius R. The electric flux through the Gaussian surface was calculated to  be 340 N.m²/C. The charge Q is equal to

a) 34 nC           b) 30 nC          c) 340 nC         d) 3 nC          e) 43 nC

10) Two large parallel nonconducting sheets carry equal but opposite uniform fixed charge on one side. If the electric field between the sheets is 340 N/C, the surface charge density on each sheet is

a) 34 nC/m²   b) 30 nC/m²   c) 340 nC/m²    d) 3 nC/m²    e) 43 nC/m²

11) The capacitance of two concentric spherical shells of radii 2.9 cm and 3.1 cm is

a) 10 pF          b) 50 pF          c) 100 pF          d) 30 pF         e) 70 pF

12) The capacitor C₁ = 1 mF is connected to a battery of 6 volts. The battery is then removed and replaced by an uncharged capacitor C₂ = 2 mF. The common potential of the two capacitors is

a) 6 V              b) 2 V             c) 9 V             d) 4 V             e)12 V