This preview shows pages 1–3. Sign up to view the full content.
This preview has intentionally blurred sections. Sign up to view the full version.
View Full Document
Unformatted text preview: yang (ey942) ohw21 turner (56705) 1 This printout should have 21 questions. Multiplechoice questions may continue on the next column or page find all choices before answering. 001 10.0 points A circuit is set up as shown in the figure. L I 2 R 2 I 1 R 1 E S The switch S in the circuit shown has been closed for a long time. At t = 0, S is opened. What is the voltage V 1 across resistor R 1 as a function of time t ? 1. V 1 = parenleftbigg R 1 R 1 + R 2 E parenrightbigg e R 1 R 2 t/ [( R 1 + R 2 ) L ] 2. V 1 = E e R 1 R 2 t/ [( R 1 + R 2 ) L ] 3. V 1 = E e R 2 t/L 4. V 1 = E e ( R 1 + R 2 ) t/L 5. V 1 = parenleftbigg R 1 R 2 E parenrightbigg e R 1 R 2 t/ [( R 1 + R 2 ) L ] 6. V 1 = parenleftbigg R 1 R 2 E parenrightbigg e R 2 t/L 7. V 1 = parenleftbigg R 1 R 1 + R 2 E parenrightbigg e ( R 1 + R 2 ) t/L 8. V 1 = parenleftbigg R 1 R 2 E parenrightbigg e ( R 1 + R 2 ) t/L correct Explanation: Just before the switch is opened ( i.e. , t 0) the current through the inductor L and resistor R 2 is I max = E R 2 , (1) since the inductor has an inductance of zero at this moment and the potential difference across the L and R 2 is the emf supplied by the battery E . When the switch is opened ( t = 0) the current in the top loop remains I max for an instant. The electrical potential drop V max 1 across resistor R 1 is V max 1 = I max R 1 , so (2) V max 1 = R 1 R 2 E V 1 = V max 1 e t/ = L R total = L R 1 + R 2 V 1 = parenleftbigg R 1 R 2 E parenrightbigg e ( R 1 + R 2 ) t/L . 002 (part 1 of 2) 10.0 points A long insulated wire with a resistance of 21 / m is to be used to construct a resistor. First, the wire is bent in half and then the doubled wire is wound in a cylinderical form, as show in figure. The diameter of the cylin drical form is 4 cm, its length is 20 cm, and the total length of wire is 15 m. Find the inductance of this wirewound reisitor. Correct answer: 0 H. Explanation: Let : = 20 cm = 0 . 2 m , d = 4 cm = 0 . 04 m , r = 21 / m , and L = 15 m . The total flux in the coil is zero, so L = 0 H . 003 (part 2 of 2) 10.0 points Find the resistance of this wirewound resis tor. yang (ey942) ohw21 turner (56705) 2 Correct answer: 315 . Explanation: Let : r = 21 / m and L = 15 m . The total resistance of the wire is R = r L = (21 / m) (15 m) = 315 . keywords: 004 (part 1 of 2) 10.0 points A solenoid has 144 turns of wire uniformly wrapped around an airfilled core, which has a diameter of 14 mm and a length of 10 . 5 cm. The permeability of free space is 1 . 25664 10 6 N / A 2 . Calculate the selfinductance of the solenoid. Correct answer: 3 . 82025 10 5 H....
View
Full
Document
 Spring '10
 Turner

Click to edit the document details