Phys%2072%201st%20LE%20AY14-15%202nd%20Sem - University of the Philippines College of Science Physics 72 Set A First Long Exam Second Semester AY

Phys%2072%201st%20LE%20AY14-15%202nd%20Sem - University of...

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University of the Philippines College of Science Physics 72 Set A First Long Exam Second Semester, AY 2014–2015 Name: Instructor: Section/Class Schedule: Student Number: Course: College:
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First Long Exam Second Semester, AY 2014–2015 Physics 72 INSTRUCTIONS: Choose the best answer and shade the corresponding circle on your answer sheet. To change your answer, cross-out and sign your original answer and then shade your new answer. No computational devices allowed (e.g. calculators, mobile phones). Any form of cheating in examinations or any act of dishonesty in relation to studies, such as plagiarism, shall be subject to disciplinary action. Following instructions is part of the exam. Useful formulas: Area Volume Sphere (radius= r ) 4 πr 2 4 3 πr 3 Cylinder (radius= r , height= h ) 2 πr 2 + 2 πrh πr 2 h sin( π/ 3) = cos( π/ 6) = 3 / 2 cos( π/ 3) = sin( π/ 6) = 1 / 2 sin( π/ 4) = cos( π/ 4) = 2 / 2 Useful constants: e - 1 . 60 × 10 - 19 C m e 9 . 1 × 10 - 31 kg 0 8 . 854 × 10 - 12 C 2 /Nm 2 k 8 . 988 × 10 9 Nm 2 /C 2 1.Square.Consider the point charge distribution in the fig-ure. What is the magnitude of the net electric force on thecharge+q0that lies in the center of the square? A.4kqq0a2B.8kqq0a2C.2k(q+Q)q0a2D.4k(q+Q)q0a22.E and F . A source charge+|Q|and a test charge-|q0|are separated by a distancer.Which of the following is/areTRUEabout the electric fieldEand electric forceFEof+|Q|on-|q0|?I.FEandEhave the same direction.II.FEandEhave opposite directions.III.|FE|and|E|are inversely proportional to one another. A – 2
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First Long Exam Second Semester, AY 2014–2015 Physics 72 3.Magnitude.Consider the diagram showing the equipo-tential lines around two identical positive charges. Whatis the relationship of the magnitude of electric field at thedifferent points? 4.dipole.An electric dipole is oriented in the uniform elec-tric field with magnitude200N/Cas shown. What is themagnitude and directionof the net torque experiencedby the electric dipole? 5.Plastic and Fur.A plastic rod (+) is rubbed on fur (-). Two balls X and Y are suspendedby insulating threads. The observations are as follows:I. Both X and Y are attracted to the plastic rod.II. X is attracted to Y.III. Y is repelled by the fur.Which of the following isTRUEregarding the system? A. X: neutralB. Y: neutralC. X: (-)D. Y: (+)A – 3
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First Long Exam Second Semester, AY 2014–2015 Physics 72
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