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The Exam: Multi-choice questions 50 pts 1 or 2 Bonus M.C. questions 5 or 10 pts 2 Written-out problems 50 pts Total 100 pts. Cheat Sheet is on Web (under ‘Exams’ link) Last HW solution on web (The test will come with one, so don’t bring one) Calculators allowed, Phones NO!.
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The Exam: Multi-choice questions 50 pts 1 or 2 Bonus M.C. questions 5 or 10 pts 2 Written-out problems 50 pts Total 100 pts Cheat Sheet is on Web (under ‘Exams’ link) Last HW solution on web (The test will come with one, so don’t bring one) Calculators allowed, Phones NO!
Written out problems -- partial credit (explain well and clearly what you’re doing) Similar to Home work problems (may even be one!) Multi-choice – no partial credit: check your math if you have time! Bonus problems – more conceptual in nature.
1) Two point charges, separated by 1.5 cm, have charge values of 2.0 and -4.0 μ C, respectively. What is the magnitude of the electric force between them? A) 400 N B) 360 N C) 320 N D) 160 N Diff: 1 Page Ref: Sec. 16.5-16.6
2) The force between a 30-μC charge and a -90- μC charge is 1.8 N. How far apart are they? A) 1.9 m B) 2.3 m C) 3.7 m D) 4.2 m Diff: 1 Page Ref: Sec. 16.5-16.5
3) What are the magnitude and direction of the electric field at a distance of 1.50 m from a 50.0-nC charge? A) 20 N/C away from the charge B) 20 N/C toward the charge C) 200 N/C away from the charge D) 200 N/C toward the charge Diff: 1 Page Ref: Sec. 16.7-16.8
3.5) A force of 10 N acts on a charge of 5.0 mC when it is placed in a uniform electric field. What is the magnitude of this electric field? A) 50 MN/C B) 2.0 MN/C C) 0.50 MN/C D) 1000 MN/C Diff: 1 Page Ref: Sec. 16.7-16.8
4) It takes 50 J of energy to move 10 C of charge from point A to point B. What is the potential difference between points A and B? A) 500 V B) 50 V C) 5.0 V D) 0.50 V Diff: 1 Page Ref: Sec. 17.1-17.4
5) A 6.0-V battery maintains the electrical potential difference between two parallel metal plates separated by 1.0 mm. What is the electric field between the plates? A) 6.0 V/m B) 600 V/m C) 6000 V/m D) zero Diff: 1 Page Ref: Sec. 17.5
6) What charge appears on the plates of a 2.0- μ F capacitor when it is charged to 100 V? A) 50 μ C B) 100 μ C C) 150 μ C D) 200 μ C Diff: 1 Page Ref: Sec. 17.7-17.9
7) 20 V is placed across a 15 μ F capacitor. What is the energy stored in the capacitor? A) 150 mJ B) 300 mJ C) 3.0 mJ D) 6.0 mJ Diff: 1 Page Ref: Sec. 17.7-17.9
8) How much charge must pass by a point in 10 s for the current to be 0.50 A? A) 20 C B) 2.0 C C) 5.0 C D) 0.050 C Diff: 1 Page Ref: Sec. 18.2
9) A light bulb operating at 110 V draws 1.40 A of current. What is its resistance? A) 12.7 B) 78.6 C) 109 D) 154 Diff: 1 Page Ref: Sec. 18.3
10) A 110-V hair dryer is rated at 1200 W. What current will it draw? A) 0.090 A B) 1.0 A C) 11 A D) 12 A Diff: 1 Page Ref: Sec. 18.5-18.6
Examples of a conceptual problems: 1) A neutral conducting sphere is placed next to a positively-charged object. The sphere is temporally grounded. What is the net charge on the sphere? Positive Negative Neutral Not enough details to reach a conclusion. Two charges are separated by a distance d and experience a force F. What happens to the force if the separation is halved and one of the charges is doubled? The forced becomes … 2 ×F 4 × F 8 × F 16 × F